OCR A Level Computer Science PDF

Head to www.savemyexams.com for more awesome resources OCR A Level Computer Science Your notes 7.2 Computational Methods Contents Computational Methods Problem Recognition Problem Decomposition Divide & Conquer Algor...

Head to www.savemyexams.com for more awesome resources OCR A Level Computer Science Your notes 7.2 Computational Methods Contents Computational Methods Problem Recognition Problem Decomposition Divide & Conquer Algorithms Use of Abstraction Backtracking Algorithms Data Mining Heuristics for Problem Solving Performance Modelling Pipelining as a Computational Method Visualisation for Problem Solving Page 1 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Computational Methods Your notes Features of Computation It's important to consider if problems can be solved using algorithms and programming code For example: Sorting a list of numbers is feasible using algorithms like quick sort or merge sort But ethical problems or social problems, like determining if a loan should be approved, may incorporate some human input that algorithms could oversimplify or misinterpret Problems that can be solved with algorithms and programming code are computational problems Real-world constraints on computable problems Practical limitations such as computing power, speed, and memory can affect whether a problem is solvable Running complex machine learning models on a regular laptop might be constrained by limited processing power and memory Challenges with resource-intensive problems Some problems are theoretically solvable but not practical due to resource limitations For example, calculating Pi to a billion decimal places is theoretically possible but impractical due to the amount of computational resources needed Advances in technology Technological improvements have expanded the types of problems that can be computationally solved For example, genome sequencing has become quicker and more affordable due to advances in technology Example Below is a table of problems identified for an online grocery business The table shows which problems are computational and a reason why Page 2 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Problem Description Computational Justification Problem Your notes (Yes or No) Inventory levels are not Yes Real-time syncing can be achieved through updated in real-time algorithms High rate of employee turnover No Root causes are likely cultural or managerial, not algorithmic Incorrectly sorted products in Yes Sorting algorithms can optimise placement for the delivery van efficiency Long wait times for customer Yes Queue algorithms can improve response times service Poor route optimisation for Yes Routing algorithms exist for this specific delivery trucks problem Inadequate marketing No Marketing strategies often require creative strategies and human-centric solutions Worked Example The table below outlines various challenges in a public transportation system. Evaluate each problem and decide whether it is computational and justify each of your decisions. Problem Description Computational Justification (Yes or No) Frequent train delays Overcrowding in peak hours Difficulty in finding the shortest route Vandalism in the stations Page 3 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Inconsistent fare pricing Inaccurate timetable Your notes How to Answer This Question 1. Review the Table: Take a moment to read through the problems listed and think about whether a computational solution would be possible 2. Fill in the Table: In the "computational" column, specify whether the problem should or should not be solved computationally 3. Justify your answers: In the last column, justify your decision for each problem briefly Answer: Problem Description Computational Justification (Yes or No) Frequent train delays Yes Real-time tracking and predictive algorithms can help in better scheduling Overcrowding in peak Yes Load-balancing algorithms can redistribute hours passengers or add more trains during peak hours Difficulty in finding the Yes Route-finding algorithms can quickly identify the shortest route most efficient path Vandalism in the stations No Requires human intervention such as increased security personnel Inconsistent fare pricing Yes Dynamic pricing algorithms can ensure fare consistency Inaccurate timetable Yes Timetabling algorithms can generate more accurate and optimised timetables Page 4 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Problem Recognition Your notes Problem Recognition What is Problem Recognition? Problem recognition is determining if there is a problem that needs to be solved For example, if customers of an online shop complain that a checkout process is slow then problem recognition can be used to determine that there is a problem to be solved and what the problem actually is In this example, the core problems might relate to how many steps exist in the process or the poor organisation of information on the page Both of these problems are possible to solve through a software solution Code can be rewritten so that the number of steps is reduced and the information can be arranged in a simpler way But not all problems should or can be solved with software Example 1: Slow response time in a GP surgery booking system A GP Surgery recently implemented an online appointment booking system to make booking an appointment with a doctor easier. While the new system was expected to make the process more efficient, patients have reported slow response times when attempting to confirm their online appointments. Some have even mentioned waiting several minutes for the confirmation screen to appear, leading to frustration and abandoned bookings. The system's sluggishness is particularly noticeable during peak hours between 8am - 9am when multiple users try booking appointments simultaneously. The big problem Slow response time: The primary issue is the slow response time in the online appointment booking system, leading to user frustration and abandoned bookings Sub problems Page 5 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources 1. Peak hour bottlenecks: The system experiences a significant peak-hour slowdown, indicating potential scalability issues Your notes 2. Delayed confirmation: Patients must wait several minutes for a confirmation screen to appear, which could point to inefficient processing of booking requests 3. User experience: Frustrated users may lose faith in the system or the GP surgery, possibly affecting its reputation 4. Abandoned bookings: The slow system is causing patients to abandon their appointments, meaning they are not seeking help with their health Example 2: Low employee morale and high turnover rates in a sales team A medium-sized company specialising in consumer electronics is experiencing high turnover rates in its sales team. Employee morale is notably low, and several exit interviews reveal that team members feel undervalued and overstressed. Sales targets are frequently unmet, and the remaining team members feel demoralised by the constant departures. Management is concerned that this ongoing issue may start affecting the overall performance and reputation of the company. The big problem Low employee morale and high turnover: The core issue is the high employee turnover rate and declining morale, which affects both team performance and the company's reputation Sub problems 1. Unrealistic sales targets: Employees feel that the sales goals set by management are too challenging to achieve, causing stress 2. Lack of support: There is a feeling among team members that they lack the necessary support and resources to perform well 3. Poor work-life balance: Long working hours and high stress levels contribute to an imbalanced work- life equation 4. Team cohesion: The frequent departures disrupt team cohesion, affecting collaborative efforts and reducing overall productivity In this case, problems like low morale, unrealistic targets, and lack of emotional support are largely cultural and psychological issues and can't be directly solved with software Page 6 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Some software solutions may exist to help, such as project management, or somewhere to record and analyse why employees are leaving Your notes But the big problem requires human-centric solutions like revised management practices, team- building exercises, and counselling services Page 7 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Problem Decomposition Your notes Problem Decomposition What is Decomposition? Decomposition is breaking down a big problem into smaller problems so that they can be solved independently Programmers use decomposition to: Break problems down Identify the steps, parts or processes involved in a problem Identify reusable components Split tasks between programmers In the case of slow appointment booking, you could decompose the problem into issues such as server limitations during peak hours, inefficient backend algorithms, and user interface delays Process of decomposition to break problems down Using abstraction to design a solution Before we start to break problems down, it is often useful to apply the rules of abstraction to the problem Page 8 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Applying abstraction will remove non-essential elements and that programmers can focus on critical aspects for problem-solving Your notes When addressing the slow booking system, a programmer could ignore elements like the system's colour scheme or graphics and focus on critical performance metrics such as server response time and database query efficiency Decomposing slow response times problem 1. Big problem: Slow response times during the online appointment booking process 2. Decompose into sub-problems: Server limitations causing bottlenecks during peak hours Inefficient algorithms leading to delayed confirmation screens Poor user interface contributing to an overall bad user experience 3. Prioritise sub-problems: 1. Address server limitations, as solving this could have a broad impact on system performance 2. Look into optimising algorithms to speed up the booking and confirmation process 3. Lastly, make user interface improvements to enhance user experience, possibly mitigating some of the frustration caused by slow response times Worked Example A popular online retail platform has recently faced significant problems with its recommendation system. Customers complain that the recommendations are not relevant, and this is affecting sales figures. Analyse the problems facing the recommendation system of the online retail platform. Decompose the problem into smaller components and discuss possible software solutions. What are the limitations of relying solely on software to improve the recommendation system? How to answer this question: 1. Introduction: Introduce the scenario and pinpoint the main problem: the ineffective recommendation system affecting sales 2. Decomposition: Break down the issue into sub-problems such as data quality, algorithmic inefficiency, and lack of user input 3. Software Solutions: Propose software-related solutions like machine learning algorithms, improved data collection, and user interface changes for better user feedback Page 9 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources 4. Limitations: Discuss why software solutions alone might not be sufficient to solve the problem completely Answer: Your notes The online retail platform faces a significant issue with its recommendation system, impacting customer satisfaction and sales. The problem can be decomposed into several smaller components: poor data quality, inefficient recommendation algorithms, and a lack of an interface for users to give feedback on recommendations. Software solutions can play a vital role in addressing these issues. Machine learning algorithms can be developed to make more precise recommendations. Data quality can be improved by incorporating a more diverse set of user activities and perhaps by using third-party data. User interface improvements could allow customers to provide immediate feedback on recommendations, which could further refine the algorithm. However, even the most advanced software solutions have limitations. For instance, without human input, they can't capture real-world influences on customer behaviour or adapt to rapid market changes. Acceptable answer you could have given instead: The online retailer is struggling with an ineffective recommendation system that needs improvement. This problem can be broken down into issues like inadequate data quality, outdated algorithms, and missing user feedback mechanisms. Software solutions are essential for solving these problems. Upgrading the algorithms and improving data quality can make the recommendations more relevant. Moreover, incorporating a user feedback feature can also help refine the system. However, software alone might not be a complete solution as it can't account for every variable affecting customer behaviour or rapid changes in consumer trends. Page 10 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Divide & Conquer Algorithms Your notes Divide & Conquer Algorithms What is the Divide & Conquer Strategy? Divide and conquer is a strategy to make a complex task easier by breaking it into smaller, more manageable tasks For example, organising a large conference can be split into smaller tasks such as booking the venue, coordinating with speakers and marketing Implementing divide and conquer Divide and conquer contains three steps: Divide - The problem needs to be broken down into sub-problems Conquer - The sub-problems then need be solved independently Combine - The solutions to the sub-problems can then be combined to form the overall solution to the problem For example, in home renovation, the project can be broken down into individual rooms or specific elements such as flooring, painting and electrics Page 11 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Process of divide and conquer to solve problems Benefits Drawbacks Your notes Divide and conquer can make programs more time Not all problems can be broken down and efficient. solved independently. As problems are divided into sub-problems they can It can possibly cause stack overflows if make effective use of cache memory. recursion is being used. Task parallelism This is when several tasks or sub-tasks can be carried out concurrently (at the same time) to speed up the overall completion time For example, on a factory assembly line, different components of a product can be put together at the same time by different teams or machines Worked Example You are the lead software engineer for a company building an e-commerce platform. Your team has been tasked with improving the website's search functionality, which has recently been sluggish due to an exponential growth in the number of products available. Describe how you would use the divide and conquer strategy and task parallelism to tackle this problem. Make sure you provide specific examples for each. How to answer this question: 1. Introduction: Briefly explain the problem of sluggish search functionality in the e-commerce platform 2. Divide and conquer: Describe how you would break the problem into smaller, more manageable tasks For example, consider breaking down the search process into tasks like query parsing, data retrieval, and front-end rendering 3. Task parallelism: Explain how tasks or sub-tasks can be executed simultaneously to speed up the problem-solving For instance, data retrieval can be parallelised by dividing the product database into smaller chunks that can be searched simultaneously Answer: Page 12 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources The issue at hand is the slow search functionality on the e-commerce platform. This is a critical problem as it hampers the user experience and could decrease sales. Your notes The problem can be divided into smaller, more manageable parts to approach this issue efficiently. Specifically, we can isolate query parsing, which involves translating user text input into a query. We could work on data retrieval, where the relevant product information is fetched from the database as well as front-end rendering which is responsible for displaying the products to the users. Once the problem is segmented, we can apply task parallelism to expedite the resolution. During the data retrieval process, we can partition the product database into smaller index-based segments, allowing multiple server instances to search them simultaneously. Concurrently, front- end rendering can implement lazy loading techniques to begin displaying products as they are retrieved, thus improving the speed of the search function. We can notably improve the search functionality and user experience by employing both divide and conquer and task parallelism. Acceptable Answer You Could Have Given Instead Our website's slow search function needs to be fixed. The problem could be broken down into a few parts: improving the search algorithm making our database faster optimising the user interface We can work on multiple steps simultaneously to solve this problem. For instance, one team can focus on the database while another works on the user interface. This approach would help make the search function faster and satisfy our users. Both answers effectively address the problem but vary in the depth and clarity with which they explain the concepts of divide and conquer and task parallelism. Page 13 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Use of Abstraction Your notes Use of Abstraction Before revising the Use of Abstraction it is important to have a deep understanding of the concept of Thinking Abstractly What is Abstraction? Abstraction is the removal of unnecessary components of a problem to allow focus on only those that are necessary Without abstraction, many real world applications would have far too many variables to take into consideration Use of Abstraction - Computer Games Computer games use a large amount of abstraction, removing the elements that a user does not need to consider in order to enjoy playing the game Page 14 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources When using abstraction in computer games which are designed to simulate real life, the aim is to make the game realistic and visually appealing whilst keeping the game fun to play Your notes In a game that simulates a sport, it is important to the user that visually they recognise the environment and when they perform an action, they see a response However, users do not need to know the complex algorithms used to control the non player characters (NPCs) Use of Abstraction - Cooking with a Recipe When cooking with a recipe, the concept of abstraction has already been applied The purpose of a recipe is for the user to follow it and end up with the desired result For example, in a recipe that asks a user to ‘brown’ an ingredient, they do not need to understand the chemistry behind the process, only the desired output in order to move on to the next step Abstraction gives a user the ability to focus on the recipes intent, rather than the science Use of Abstraction - Driving a Car Page 15 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes When driving a car, the driver uses a key or button to start the engine, and uses pedals to start and stop The driver does not need to know the intricacies of how the engine works to complete the task Abstraction empowers people to utilise complex machines like cars Page 16 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Backtracking Algorithms Your notes Backtracking Algorithms What is Backtracking? Backtracking is a technique that is used when you don’t have enough information to find a solution to a problem or if you have many possible ways of solving a problem It will therefore explore all possible paths in the search space to determine if these come to dead ends It will build up partial solutions to a large problem incrementally and then if the solution fails at some point, the partial solutions are abandoned and the search begins again at the last potentially successful point Backtracking is ideal if you are trying to solve logic problems, however, is not ideal for solving strategic problems For example, backtracking can be used to navigate around a maze to move forward until a wall is hit (dead end), then backtrack to try another route Example use Backtracking can be particularly useful when traversing data structures such as trees or graphs as these have multiple paths that can lead to the desired solution In a binary search tree, backtracking helps to return from leaf nodes (dead ends) so that other subtrees can be explored Page 17 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Using backtracking to solve problems Benefits Drawbacks Your notes It is guaranteed to find a solution if one Is not ideal for solving strategic problems. exists. It is easy to implement and use. Depending on the problem that you are trying to solve, it can have a high time complexity. It can be be applied to a variety of logic If there are lots of different solutions to a problem, it is not problems. always the most efficient method. It will comprehensively explore all possible It can consume a lot of memory. paths to the desired solution. Although it may find a solution to the problem, the solution may not always be the best solution available. It will often require a complete search of the entire solution space. Worked Example You are developing a maze-solving application where a user-controlled character needs to navigate from the start point to the end point. The maze contains several dead ends and multiple pathways to reach the destination. Describe how backtracking can be used to solve this problem. You should include the steps involved and any advantages or limitations of using backtracking for this scenario. How to answer this question: 1. Introduction: Explain what is meant by the term 'backtracking' and why it's suitable for solving maze problems 2. Algorithm Steps: Give the steps the backtracking algorithm would follow to solve the maze problem 3. Advantages: Give the advantages of using backtracking 4. Limitations: Give any limitations of using backtracking Page 18 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Answer: Backtracking is an algorithmic approach that builds a solution incrementally. It's ideal for solving Your notes maze problems because it explores each path until it reaches a dead end and then retreats (backtracks) to another pathway to explore. The backtracking algorithm would start at the maze entrance and move step-by-step towards the exit, marking visited areas of the maze. Upon reaching a dead end, the algorithm would backtrack to the last unvisited branch. The primary advantage of backtracking is that it guarantees a solution if one exists. It's efficient and can be easily implemented. However, backtracking can be slow for complex or large maze problems and it may not always find the best solution available. Backtracking offers a reliable, straightforward way to solve maze problems despite its limitations. Acceptable answer you could have given instead: Backtracking is good for solving maze problems as it can find a path from start to finish. The algorithm starts at the entrance and moves through the maze, backtracking when it hits a wall (dead end) until it finds the exit. This method will find a solution if one is available, however, it may take longer for bigger mazes. Backtracking is a suitable method for solving mazes, although it may have some downsides, like speed and poor time complexities. Page 19 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Data Mining Your notes Data Mining What is Data Mining? Data mining is when large quantities of data are turned into useful information so that patterns can be found It can be used to search for relationships and facts that are probably not immediately obvious to people It will extract valuable insights from large sets of data using algorithms and statistical methods Data mining is used in many fields, including retail, healthcare, and finance, to make informed decisions The diagram below shows useful business insights that can be gained from data collected by an online grocery business Page 20 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes How data mining can be used to generate insights Benefits Drawbacks Data mining can be used to identify patterns and trends It requires very powerful computers with a lot that may not be immediately obvious to humans. of processing power. It can help organisations make better future Inaccurate data can produce inaccurate predictions. results. Page 21 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Organisations can ensure demand is met during busy Although it may spot patterns and trends, it periods to stay ahead of local competition. may not explain the reasons why these exist. Your notes Example uses of data mining Retail industry Data mining algorithms can be used to analyse purchase history and browsing behaviour to provide customised product suggestions Online retailers like Amazon use purchase data to suggest items for customers based on past activity Healthcare industry Data from healthcare records and other sources can be analysed to predict disease outbreaks or patient admissions Hospitals use data mining to anticipate flu cases in the coming winter, enabling better resource allocation Finance and banking Machine learning models trained on historical data can be used to identify suspicious activities among millions of transactions Credit card companies use data mining algorithms to flag potentially fraudulent transactions in real- time Automotive industry Data collected from vehicle sensors can be used to predict when a part is likely to fail, enabling more proactive maintenance Manufacturers like Tesla collect data from electric cars to anticipate when a battery or other components may fail Entertainment and media Data mining helps understand viewer preferences and behaviour, enabling better content recommendations Streaming services like Netflix use data mining to target new shows and movies to specific audiences based on their previous viewing history Complexities in data mining Page 22 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Data mining requires knowledge of complex algorithms for data sorting, pattern recognition, and anomaly detection Your notes Running data mining algorithms within a company requires significant maintenance and expertise Companies must be careful with customer data and must ensure all mining follows the General Data Protection Regulation (GDPR) Specialist data engineers and data scientists are in short supply in industry Page 23 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Heuristics for Problem Solving Your notes Heuristics for Problem Solving What are Heuristics? Heuristics is making use of experience to find a solution to a problem quickly It uses concepts like 'rules of thumb' and 'educated guesses' to find a solution faster than traditional methods It prioritises speed and not accuracy It aims to find a solution that is 'good enough' rather than perfect Trade-off between speed and accuracy A game is called 'Hot and Cold' and the rules are as follows: A person (known as the searcher) tries to locate a hidden object by listening to clues from another person, who can only say "hotter" or "colder" based on the seeker's proximity to the hidden object "Hotter" or "colder" clues are indicators of where the object is, but they don't give an exact location Thinking about the use of heuristics in this game: If the searcher misinterprets the clues, they may get stuck in a spot that seems "hot" but is not the actual target This predicament also happens in heuristic algorithms and is known as getting stuck in a local optimum The searcher responds to feedback and gains more intelligence to find the object, usually resulting in them finding the object The method finds the object more quickly than random searching, but it doesn't guarantee the quickest or most direct route will be taken This is the same for heuristic methods, where there is a trade-off between speed and accuracy Heuristic methods in software The A* algorithm is a common example that uses heuristics in pathfinding and graph traversal The aim of the A* algorithm is to use heuristics to find a path from a start node to an end node quickly, however, the path that it finds may not always be the most efficient path possible Learn more about A* Algorithm Page 24 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Benefits Drawbacks Your notes Heuristics can usually find a solution close to the It will not guarantee that you will find the ‘best’ best solution available. solution as it aims to find a solution quickly that is ‘good enough.’ Heuristics save time as you may not to There needs to be careful consideration to be made investigate every single possibility to get a between accuracy and time. definite answer. Heuristics is very practical and can be easily The heuristic values may be incorrect which can lead implemented. to inaccurate solutions being found. Page 25 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Performance Modelling Your notes Performance Modelling What is Performance Modelling? Performance modelling is when the behaviour of something is tested or simulated before it is used in the real world It is a systematic approach that can be used for evaluating and predicting the performance characteristics of a software system Using Performance Modelling in Software Production Performance modelling can be used to help understand how the software will behave under different load conditions and configurations It uses various metrics like response time and throughput to identify potential bottlenecks which can be used by developers to address performance issues before they affect end-users It can be integrated into various stages of the software development including the: Design phase to make architectural decisions Testing phase to simulate real world scenarios and measure the software's performance Benefits Drawbacks Stress testing can ensure a system can cope with The outcome of performance modelling is only as a large set of data or a large number of users. useful as the accuracy of the data that is fed into it. You are able to predict problems and act on them If the rules that made up the model are wrong then before the problems actually occur in the real it will produce incorrect results. world. Examples of Performance Modelling Database Optimisation Performance modelling can be used to simulate different database architectures and query strategies to find the most efficient setup It can help select the best indexing strategy and estimate the query response times under varying loads Page 26 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources It may help decide between a relational database design or a single table design Caching Mechanisms Your notes By modelling how different caching strategies perform under various scenarios, optimal cache sizes can be determined Developers can assess the hit/miss ratio of caches and the latency improvements gained through caching Use of performance modelling to determine a caching mechanism Energy Efficiency For mobile or embedded systems, performance modelling can be used to estimate power consumption under different usage patterns It can be useful for battery-powered devices where power consumption is a critical factor Page 27 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Pipelining as a Computational Method Your notes Pipelining as a Computational Method Before revising pipelining as a computational method, it is important to revise the concept of pipelining within the CPU first. What is Pipelining? Pipelining is the process of carrying out multiple instructions concurrently It improves the overall efficiency and performance of a task or instruction In order to utilise pipelining it can be broken down into the following stages: 1. Break down the task - analyse the process carefully to identify the individual tasks that make up the overall job 2. Arrange in sequential order - organise the tasks into a logical sequence, where the output of one task becomes the input for the next 3. Allow multiple tasks to operate at the same time - instead of waiting for one task to fully complete before starting the next one, allow multiple tasks to operate concurrently Pipelining in Programming In languages such as Python and Java pipelining is chaining multiple instructions together Pipelining is a similar concept to an assembly line which is used to make the overall process more efficient Here is an example program written in Python that generates squared values of numbers from a list and then filters them to find only the even values 01 list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] 02 squared = [x**2 for x in list] 03 filtered = [x for x in squared if x % 2 == 0] 04 print(filtered) Line 01 creates a list of ten numbers Line 02 uses iteration to square each value in the list one by one and generate a new list called ‘squared’ Page 28 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Line 3 filters the new list, searching for each even number and adding them to a separate list called "filtered" Your notes On line 04 we print the filtered list, the final output would be: [4, 16, 36, 64, 100] In the first example commands are separated by being on their own individual numbered lines, in other languages such as Unix the ‘|’ symbol is used to separate commands Each command in the ‘pipeline’ is separated and data flows left to right An example of the ‘|’ symbol used in Unix: grep “hello” docs | grep “world” Here two grep commands (search) are chained together to perform a specific task The first grep command grep “hello” docs searches for lines that contain the word “hello” in a list of files contained in a file named ‘docs’ The pipe symbol ‘|’ connects the output of the first command to the input of the second command meaning only lines containing the word “hello” are passed to the second command The second grep command grep “world” searches for lines in the filtered results from command 1 that contain the word “world” Worked Example When a car is manufactured, the following activities take place: Designs drawn Engine developed Chassis developed Electronics planned Welding to create the body of the car Painting to protect the cars exterior Engine assembled Interior assembly Wheels attached Final inspection Define the term ‘pipelining’ Carrying out instructions concurrently The result from one process/procedure feeds into the next Explain how the principles of pipelining can be applied to ensure a car is manufactured as quickly as possible Page 29 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Identify tasks that can be carried out at the same time for example, the engine and chassis can be developed separately but at the same time once the designs have been drawn Identify tasks that must be completed in order for example, painting once the body has been Your notes created/final inspection once all other tasks have been completed Describe one example of where pipelining is user in a computer system Pipes to pass data between programs for example, the | symbol used in Unix Page 30 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Visualisation for Problem Solving Your notes Visualisation What is Visualisation? Visualisation is when data or concepts are presented in simpler form for humans to understand It will often create a graphical or visual representation of something to understand complex systems or data Benefits Drawbacks Visualisation can simplify concepts that are easier for Although it can show data in a visual way, it humans to understand. cannot explain why something is the way that it is. It can make it easier to spot new trends and patterns that Different people may interpret the have not been spotted before. visualisations in different ways. It can be used to explain complex situations to allow The way that the data is presented can have programmers to get a better understanding of the an impact on its understanding. problems of a current system. Example Uses of Visualisation Flowcharts These are diagrams that represent workflows or processes in a system They help in mapping out each step, making it easier to predict outcomes In the example below, the checkout process is a complex user journey that has to ensure users don't check out for items that are no longer available in stock When buying concert tickets or limited-edition merchandise, these are usually highly volatile episodes for a checkout server, especially when users often have multiple baskets across multiple devices, abandoning journeys and editing basket contents Page 31 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes Using flowcharts to visualise a checkout process Unified Modeling Language (UML) Diagrams These provide a standard way to visualise a system's architecture They are useful for understanding how classes and objects interact with each other Page 32 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes Using UML diagrams to visualise how objects interact with each other in a system Wireframes These are low-fidelity design plans that represent the skeletal framework of a program or website They help with layout planning and user experience design Page 33 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes Using wireframe diagrams to visualise how a user interface will look Page 34 of 34 © 2015-2025 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers