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Questions and Answers
Which of the following is the primary focus of the initial 'Problem Understanding' phase in the data analysis process?
Which of the following is the primary focus of the initial 'Problem Understanding' phase in the data analysis process?
During the 'Data Understanding' phase, what is one of the core questions you should aim to answer?
During the 'Data Understanding' phase, what is one of the core questions you should aim to answer?
Which of these actions is primarily performed during the 'Data Preparation' phase?
Which of these actions is primarily performed during the 'Data Preparation' phase?
What does the data preparation phase not primarily involve?
What does the data preparation phase not primarily involve?
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Which of these is a key purpose of the 'Data Understanding' phase?
Which of these is a key purpose of the 'Data Understanding' phase?
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If a data analysis project has an unclear business problem, which phase would likely need to be revisited or given more focus to provide clarity?
If a data analysis project has an unclear business problem, which phase would likely need to be revisited or given more focus to provide clarity?
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What activity from the list below is more likely to be done in data preparation phase rather than in data understanding?
What activity from the list below is more likely to be done in data preparation phase rather than in data understanding?
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Which of these is the typical order of phases in a data analysis process?
Which of these is the typical order of phases in a data analysis process?
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What impact do outliers have on machine learning models?
What impact do outliers have on machine learning models?
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Which of the following methods is NOT used to detect outliers?
Which of the following methods is NOT used to detect outliers?
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What is the primary purpose of feature scaling?
What is the primary purpose of feature scaling?
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What is the primary focus of the data analysis process during the 'Modeling' phase?
What is the primary focus of the data analysis process during the 'Modeling' phase?
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What is the mean and standard deviation of normalized values after applying the z-score standardization?
What is the mean and standard deviation of normalized values after applying the z-score standardization?
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In min-max normalization, what is the typical range that the original data is transformed into?
In min-max normalization, what is the typical range that the original data is transformed into?
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Which of these activities is a key component of the 'Evaluation' phase in data analysis?
Which of these activities is a key component of the 'Evaluation' phase in data analysis?
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What is the primary goal of the 'Deployment' phase in data analysis?
What is the primary goal of the 'Deployment' phase in data analysis?
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A machine learning model has an AUC score of 0.65. How would this model be classified?
A machine learning model has an AUC score of 0.65. How would this model be classified?
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What does the term 'Machine learning models' refer to?
What does the term 'Machine learning models' refer to?
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Why is Python a popular language for machine learning?
Why is Python a popular language for machine learning?
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Which of the following best describes the role of libraries like Scikit-learn, TensorFlow, and Pandas in Python for machine learning?
Which of the following best describes the role of libraries like Scikit-learn, TensorFlow, and Pandas in Python for machine learning?
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What is the formula for calculating the False Positive Rate (FPR)? given TP (True Positives), TN (True Negatives), FP (False Positives), FN (False Negatives)
What is the formula for calculating the False Positive Rate (FPR)? given TP (True Positives), TN (True Negatives), FP (False Positives), FN (False Negatives)
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In the context of the data analysis process, which phase directly precedes the 'Deployment' phase?
In the context of the data analysis process, which phase directly precedes the 'Deployment' phase?
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What is the primary reason given in the content for why the creation of a model is generally not the end of a project?
What is the primary reason given in the content for why the creation of a model is generally not the end of a project?
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Besides readability, what specific advantage does the content mention regarding Python's use in machine learning?
Besides readability, what specific advantage does the content mention regarding Python's use in machine learning?
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According to the CRISP-DM methodology, which phase directly follows 'Data Understanding'?
According to the CRISP-DM methodology, which phase directly follows 'Data Understanding'?
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In the context of machine learning, what is the primary reason for preprocessing a dataset before applying an algorithm?
In the context of machine learning, what is the primary reason for preprocessing a dataset before applying an algorithm?
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What is the singular form of 'data'?
What is the singular form of 'data'?
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In Euclid's work 'Dedomena', what is the term 'data' considered to be?
In Euclid's work 'Dedomena', what is the term 'data' considered to be?
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If a dataset is represented as a matrix of type m x n
, what does m
represent?
If a dataset is represented as a matrix of type m x n
, what does m
represent?
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In record-based data, what is another term for output variables?
In record-based data, what is another term for output variables?
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Which of the following best describes how a record is structured in a typical dataset?
Which of the following best describes how a record is structured in a typical dataset?
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What is a fundamental characteristic of input variables in the context of machine learning?
What is a fundamental characteristic of input variables in the context of machine learning?
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What is the primary purpose of using descriptive statistics in data analysis?
What is the primary purpose of using descriptive statistics in data analysis?
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What does a distribution in a dataset represent?
What does a distribution in a dataset represent?
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Which of the following is NOT considered a central tendency measure?
Which of the following is NOT considered a central tendency measure?
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How is the mean calculated for a given dataset?
How is the mean calculated for a given dataset?
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What does the median represent in a sorted dataset?
What does the median represent in a sorted dataset?
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What is the primary focus of spread or dispersion measures in statistics?
What is the primary focus of spread or dispersion measures in statistics?
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Which measure of central tendency is most affected by outliers in a dataset?
Which measure of central tendency is most affected by outliers in a dataset?
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What is the most appropriate way to describe a sample of data using the measures described in the document?
What is the most appropriate way to describe a sample of data using the measures described in the document?
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How are anomalies typically detected, according to the text?
How are anomalies typically detected, according to the text?
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What is the primary function of Principal Component Analysis (PCA) in the context of dimensionality reduction?
What is the primary function of Principal Component Analysis (PCA) in the context of dimensionality reduction?
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Which kernel is most commonly used in kernelized machine learning techniques?
Which kernel is most commonly used in kernelized machine learning techniques?
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What does the central limit theorem indicate about the sampling distribution as the sample size increases?
What does the central limit theorem indicate about the sampling distribution as the sample size increases?
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According to the central limit theorem, what happens to the mean of the sample as sample size increases?
According to the central limit theorem, what happens to the mean of the sample as sample size increases?
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What is the role of sampling in the data analysis process?
What is the role of sampling in the data analysis process?
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What is the initial move in the data analysis system toward easily understanding and communicating information?
What is the initial move in the data analysis system toward easily understanding and communicating information?
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What happens to the standard deviation of the sample as sample size increases, according to the central limit theorem?
What happens to the standard deviation of the sample as sample size increases, according to the central limit theorem?
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Flashcards
Problem Understanding
Problem Understanding
The first step in the data analysis process, where you clearly define the project goals and translate them into a data-driven problem statement.
Data Understanding
Data Understanding
This phase involves gaining a deep understanding of the data, answering crucial questions about its origin, collection methods, and meaning.
Data Preparation
Data Preparation
Involves preparing your raw data for analysis by cleaning, transforming, and combining datasets to build a cohesive and usable dataset.
Modeling
Modeling
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Evaluation
Evaluation
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Deployment
Deployment
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Modeling in Data Analysis
Modeling in Data Analysis
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Evaluating Models in Data Analysis
Evaluating Models in Data Analysis
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Deploying Models in Data Analysis
Deploying Models in Data Analysis
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Why is Python preferred for machine learning?
Why is Python preferred for machine learning?
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What libraries support machine learning in Python?
What libraries support machine learning in Python?
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What are the benefits of Python libraries for machine learning?
What are the benefits of Python libraries for machine learning?
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What is data analysis?
What is data analysis?
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Why is data analysis important?
Why is data analysis important?
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Mean
Mean
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Median
Median
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Spread or Dispersion Measures
Spread or Dispersion Measures
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Distribution
Distribution
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Descriptive Statistics
Descriptive Statistics
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Central Tendency Measures
Central Tendency Measures
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Data Cleaning
Data Cleaning
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What is data in the context of machine learning?
What is data in the context of machine learning?
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What is a record in machine learning?
What is a record in machine learning?
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What are attributes in machine learning?
What are attributes in machine learning?
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What are input variables in machine learning?
What are input variables in machine learning?
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What are output variables in machine learning?
What are output variables in machine learning?
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What are transaction-based sets in machine learning?
What are transaction-based sets in machine learning?
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What is CRISP-DM and its purpose?
What is CRISP-DM and its purpose?
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Why is data preprocessing important for machine learning?
Why is data preprocessing important for machine learning?
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Anomaly Detection
Anomaly Detection
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Principal Component Analysis (PCA)
Principal Component Analysis (PCA)
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Kernel Methods
Kernel Methods
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Central Limit Theorem
Central Limit Theorem
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Sample (in Data Analysis)
Sample (in Data Analysis)
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Sampling
Sampling
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Data Visualization
Data Visualization
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Normal Distribution Assumption
Normal Distribution Assumption
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What are outliers?
What are outliers?
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How do outliers impact predictive models?
How do outliers impact predictive models?
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What is a Box Plot?
What is a Box Plot?
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What is a Z-score?
What is a Z-score?
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What is data transformation?
What is data transformation?
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What is Z-score standardization?
What is Z-score standardization?
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What is Min-Max normalization?
What is Min-Max normalization?
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What is AUC in Machine Learning?
What is AUC in Machine Learning?
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Study Notes
Machine Learning
- Machine learning (ML) is a computer science field studying algorithms and techniques for automating solutions to complex problems.
- Coined around 1960, it combines "machine" (computer, robot, etc.) and "learning" (acquiring or discovering patterns).
Bibliography
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Provides a list of various books and resources on data mining and machine learning.
-
Includes URLs for additional sources.
Big Data
- The University of Lodz Library holds approximately 2.8 million volumes.
- Assuming an average document size of 1MB, the library's equivalent digital storage would be 30 terabytes.
- A courier company's shipment database is roughly 20 terabytes.
- The documents list various unit prefixes for data storage (KB, MB, GB, TB, PB, EB, ZB, YB, YIB).
Machine Learning Definition
- Data mining is the art and science of intelligent data analysis aiming to uncover meaningful insights and knowledge from data.
- This often involves creating models that capture the essence of discovered knowledge, enabling better understanding and prediction.
Data Mining vs Machine Learning
- Data mining focuses on discovering patterns in data that are precise, new, useful, and understandable.
- Machine learning uses algorithms to automatically improve through data-based experience, constructing models to predict future results. This often employs data mining techniques.
What is not Data Mining and Machine Learning
- Data mining and Machine learning are distinct from OLAP (online analytical processing).
- OLAP focuses on querying and summarizing data, not on extracting patterns or making predictions.
Data Analysis Process
-
The Cross-Industry Standard Process for Data Mining (CRISP-DM) is a widely used framework for data analysis projects.
-
CRISP-DM includes six phases:
-
Problem understanding (Business understanding)
-
Data understanding
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Data preparation
-
Modeling
-
Evaluation
-
Deployment
-
These phases are iterative and often overlap.
Data Analysis Process - Specific steps
- Problem Understanding/Business Understanding: Understanding the business aims and requirements
- Data Understanding: Becoming familiar with the data, identifying data quality issues
- Data Preparation: Constructing the final dataset from raw data (e.g., joining multiple data sets, cleaning, and reducing variables)
- Modeling: Selecting and applying modeling techniques, calibrating parameters
- Evaluation: Determining whether the model fits assumptions, evaluating performance against business objectives
- Deployment: Implementing and presenting the model's insights in a user-friendly format
Data Quality
- Machine learning algorithms are sensitive to data quality, meaning flawed data leads to erroneous results.
- "Garbage in, garbage out" (GIGO) is a principle emphasizing data quality's importance.
- Data quality has three fundamental properties: completeness, correctness, and actuality.
Types of Variable
- Data type influences data analysis and visualization.
- Qualitative (categorical): Non-numerical data (names, labels).
- Nominal: Unordered categories (e.g., colors, names of products)
- Ordinal: Ordered categories (e.g., ratings, education levels)
- Quantitative (numerical): Measured using integer or real values
- Discrete: Finite countable values (e.g., number of items).
- Continuous: Uncountable values (e.g., height, weight)
Qualitative data - types
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Nominal attributes - labels or names that represent different categories
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Ordinal attributes - have a meaningful order or ranking.
Quantitative data - types
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Discrete attributes - those are finite countable set of values.
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Continuous attributes - have uncountable values, such as height or weight.
Single-valued variables
- Single-valued variables do not contain information and therefore are not used in data analysis.
- Such variables should be checked in data for analysis to ensure the model performance is not impacted.
Types of Data - Transaction-based sets
- Data organized as transactions for the business analysis of items purchased by customers.
- Each transaction is represented by a vector of items.
Data in graph form
- Data visualizations often depict relationships using graphs with vertices storing data and edges for relationships.
Data Quality - More Information
- Data quality is critical in building machine learning models as inaccuracies can result in poor performance.
Noise in Data
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Label noise: Incorrect labeling of observations.
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Inconsistent observations: Erroneous or inconsistent data.
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Classification errors: Observations labeled as a class they don't belong to.
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Data noise is synonymous with corrupted data for analysis purpose.
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Attribute noise: Incorrect or missing attribute values.
Data Analysis Engineering
- Data science depends on several factors like programming, machine learning, statistics, data engineering, and visualization.
Python and Machine Learning
- Python is a popular choice for machine learning due to its readability, intuitive syntax, and extensive libraries (e.g., Scikit-learn, TensorFlow, PyTorch).
Python 4 ML - Libraries
- NumPy is a fundamental library for scientific computing, providing support for arrays and matrices.
- Pandas is essential for data manipulation and analysis, providing data structures for numerical tables and time series.
- Matplotlib is excellent for creating static, interactive, and animated visualizations in Python.
- Scikit-learn provides supervised and unsupervised learning algorithms, along with relevant tools for model selection and evaluation.
- SciPy extends capabilities of NumPy with optimization, regression, interpolation, eigenvector decomposition.
Data Analysis Process - Flow
- Dataset: Raw and Matrix data.
- Training Set Training data for model building
- Test Set: Assessing model performance on unseen data to test accuracy and generalize well.
Data Pre-processing
- Data preprocessing is crucial (typically 70-80% of the knowledge discovery process).
- Includes: data cleaning (fixing errors, removing duplicates, etc.), restructuring data to match required format, merging datasets, etc.
Data Types (summary)
- Data classification can be by attributes (Categorical, numerical, ordered data, etc.)
Data Visualization (general)
- Visualizing data is valuable in understanding trends, outliers, distributions, relationships, etc.
- Uses visual elements such as charts, graphs, plots, and maps.
Data Visualization - Comparisons
- Comparison visualizations illustrate differences over time.
- Box plots effectively compare distributions of continuous variables across categories.
Visualizing numeric features - Box plots
- Displays five-number summary (minimum, 1st quartile, median, 3rd quartile, maximum) and outliers individually.
Data Visualization
-
Scatterplots show relationships between two or more continuous variables.
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Histograms visually represent the distribution of numerical data values by showing how frequently values appear.
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Heatmaps are intelligent analytical tools using a color system to show various different values.
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Pair plots show relationships among pairs of variables in numerical datasets providing distributions and correlations.
Knowledge and Information
- Data provides raw, descriptive facts and figures; information is a result of interpreting or processing data; knowledge often arises from observing or reasoning across multiple data points, potentially revealing deeper insights or patterns not directly apparent from individual data points.
Data Analysis
- Data analysis (e.g. via CRISP-DM methodology) involves understanding issues, data examination and preparation, selection/fitting/training and evaluation of a model for a particular issue.
Normal Distribution
- A symmetrical, bell-shaped continuous probability distribution, used in many machine learning algorithms and statistical methods.
- The mean, median, and mode are at the peak.
- Measures of spread are commonly related to standard deviation; 68% data in one standard deviation from the mean; 95% in 2 standard deviations.
Central Limit Theorem
- A statistical theorem stating that the sampling distribution of the mean approaches a normal distribution as the sample size increases.
- This is important for statistical tests and estimations.
Data Analysis Process - Data collection (sampling)
- A sample is a smaller representative subset of a larger population to avoid sampling the entire population.
Data Analysis Process - Data Visualization
- A process enabling the visualization of patterns and insights present in large data sets,
- Charts, graphs, and similar visual representations are created to showcase different trends present in data sets.
Machine Learning Models - Supervised learning
- Predicts a target output based on input data (for example, credit risk in loan applications.).
- Includes algorithms like Support Vector Machines (SVM), decision trees, k-nearest neighbors (KNN), logistic regression, etc.
Machine Learning Models - Unsupervised Learning
- Aims to recognize patterns and relationships within data without needing a pre-defined classification.
- Includes techniques like clustering (group similar data points), dimensionality reduction (reducing the number of variables), association rules (finding correlations between data points), etc.
Classification
- Classification aims at assigning observations into categories.
- Common algorithms include:
- k-Nearest Neighbors (k-NN)
- Decision Trees
- Support Vector Machines (SVM)
- Neural Networks (NN)
- Naive Bayes
Regression
- Aims at predicting continuous numerical values. (for example, house prices, salaries).
- Common algorithms include:
- Linear Regression
- Multiple Linear Regression
- Decision Trees
- Neural Networks
Data Analysis - Model evaluation
- Evaluating model performance includes measuring accuracy, error rate, precision, recall, F1-score, and the area under the ROC curve (AUC)
- These help gauge how well the model generalizes from training to unseen data.
Data Analysis - Model Evaluation
- Measures that consider the importance of each class to be correctly identified, such as precision, recall, F1-score, or Kappa, are considered.
Data Analysis - Resampling and k-Fold Cross-Validation
- Techniques repeatedly using different samples of data sets to train and evaluate a model which enables the generalization of the model to unseen data, avoiding overfitting.
Data Analysis - Leave-one-out Cross-Validation
- Specialized k-Fold cross-validation technique considering each observation for estimating generalizability, but with high computational cost.
Data Analysis - Boosting (general)
- An approach to strengthen weak learners (e.g. decision tree) by re-evaluating the misclassified observations and constructing successive learners.
- Different types of boosting algorithms are available for regression or classification problems.
Data Analysis - XGBoost
- A type of boosting algorithm but with regularization to prevent overfitting or over-complex models.
Data Analysis - Gradient Boosting (general)
- Ensembles a series of weak models (e.g., single decision trees.) to enhance performance.
- Aims is to minimise loss function (e.g., mean squared error (MSE) ) in a iterative approach using a gradient descent method.
Data Analysis - Gradient descent
- Gradient descent finds a local minimum of a mathematical function by taking iterative steps (through a pre-defined learning rate) in the descent direction of the function using its gradient.
Data Analysis - Underfitting
- The model is too simplified for representing complex data or patterns.
- Techniques to avoid this are to increase model complexity (adding more features/parameters or making it more complex) and increasing dataset size for model learning.
Data Analysis - Overfitting
- The model is too complex and has learned the training data and their noise, not the underlying patterns in the data.
- To avoid this, improve data quality, increase training data size, and reduce model complexity. Techniques are to increase training data, improve data quality.
Data Analysis - Bias-Variance Tradeoff
- A balance concept in model building that strives to minimize both bias and variance.
- Both high bias and high variance result in poor out-of sample predictions.
Data Analysis - Quantile-Quantile (Q-Q) Plots
- Useful to assess whether data follow some particular probability distribution (for example normal distribution).
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Description
Test your knowledge on the phases of the data analysis process, including problem understanding, data understanding, and data preparation. This quiz covers key concepts, challenges, and methods used during these vital phases of data analysis.