MATH 50 Engineering Data Analysis Lecture Slides PDF - Mariano Marcos State University Philippines

MATH 50 – ENGINEERING DATA ANALYSIS Unit 1. Obtaining Data Engr. Roxanne Joy O. Antonio Mariano Marcos State University College of Engineering Department of Agricultural and Biosystems Engineering  Outline 1. Introduction 2. Types of D...

MATH 50 – ENGINEERING DATA ANALYSIS Unit 1. Obtaining Data Engr. Roxanne Joy O. Antonio Mariano Marcos State University College of Engineering Department of Agricultural and Biosystems Engineering  Outline 1. Introduction 2. Types of Data 3. Methods of Data Collection 4. Introduction to Design Experiments  Objectives After careful study of this chapter, students should be able to do the following: 1. discuss the different terms related to data analysis; 2. classify data as either qualitative or quantitative; 3. classify variables as either discrete or continuous; 4. discuss how measurements or data are generated; 5. describe data and how they are used for making engineering decisions; 6. demonstrate an understanding of the different methods of obtaining data; and 7. explain the procedures in planning and conducting surveys and experiments. Introduction What Engineers Do? An engineer is someone who solves problems of interest to society with the with the efficient application of scientific principles by: Refining existing products Designing new products or processes The Engineering Method Data are facts, figures and information collected on some characteristics of a population or sample. These can be classified as qualitative or quantitative data. factual information (as measurements or statistics) used as a basis for reasoning, discussion, or calculation. information output by a sensing device or organ that includes both useful and irrelevant or redundant information and must be processed to be meaningful. Statistics Deals with the collection, science of learning from data, presentation, analysis and use and of measuring, controlling, of data to make decisions, and communicating solve problems, and design uncertainty; and it thereby products and processes provides the navigation essential for controlling the course of scientific and societal advances 3 Reasons to Study Statistics 1. Being informed Are kids ruder today than in the past? An article titled “Kids Gone Wild” summarized data from a survey conducted by the Associated Press. Nearly 70% of those who participated in the survey said that people were ruder now than 20 years ago, with kids being the biggest offenders. As evidence that this is a serious problem, the author of the article also referenced a 2004 study conducted by Public Agenda, a public opinion research group. That study indicated that more than one third of teachers had either seriously considered leaving teaching or knew a colleague who left because of intolerable student behavior. (New York Times, November 27, 2005) 3 Reasons to Study Statistics 2. Making informed judgements 3. Evaluating Decisions that Affect Your Life While you will need to make informed decisions based on data, it is also the case that other people will use statistical methods to make decisions that affect you as an individual. Statistical Terms Population Parameter Sample Statistic Data Constant Ungrouped data Variable Grouped Data Example We are going to figure out if all Female over 30 years old in Batac City can lose weight with Vegan diet Data Age of subject, weight gain/loss, name or number of subject Population All female over 30 in Batac City Sample Only the female in our study in Barangay 1 Parameters Average weight gained/loss of all female over 30 Statistics Average weight gained/loss of female in the study Variable Starting weight of each sample Descriptive Statistics deals with the procedures that organize, summarize and describe quantitative data. It seeks merely to describe data. Common tools are : Measures of Central Tendency ( Mean, Median & Mode) Measures of Variability (Range, Variance, Standard Deviation) Example In a Midterm Exam, 25 out of 50 students were able to receive a passing grade. The average score of the class is 75 out of 100 Inferential Statistics deals with making a judgment or a conclusion about a population based on the findings from a sample that is taken from the population. Common tools are : Hypothesis Testing Regression Analysis Example 20% living in our subdivision prefer to drive Toyota cars. The Data Analysis Process 1. Understanding the nature of the problem. 2. Deciding what to measure and how to measure it. 3. Data collection. 4. Data summarization and preliminary analysis. 5. Formal data analysis. 6. Interpretation of results. A Proposed New Treatment for Alzheimer’s Disease The article “Brain Shunt Tested to Treat Alzheimer’s” (San Francisco Chronicle, October 23, 2002) summarizes the findings of a study that appeared in the journal Neurology. Doctors at Stanford Medical Center were interested in determining whether a new surgical approach to treating Alzheimer’s disease results in improved memory functioning. The surgical procedure involves implanting a thin tube, called a shunt, which is designed to drain toxins from the fluid-filled space that cushions the brain. Eleven patients had shunts implanted and were followed for a year, receiving quarterly tests of memory function. Another sample of Alzheimer’s patients was used as a comparison group. Those in the comparison group received the standard care for Alzheimer’s disease. After analyzing the data from this study, the investigators concluded that the “results suggested the treated patients essentially held their own in the cognitive tests while the patients in the control group steadily declined. However, the study was too small to produce conclusive statistical evidence.” Based on these results, a much larger 18- month study was planned. That study was to include 256 patients at 25 medical centers around the country. This study illustrates the nature of the data analysis process. A clearly defined research question and an appropriate choice of how to measure the variable of interest (the cognitive tests used to measure memory function) preceded the data collection. Assuming that a reasonable method was used to collect the data (we will see how this can be evaluated in Chapter 2) and that appropriate methods of analysis were employed, the investigators reached the conclusion that the surgical procedure showed promise. However, they recognized the limitations of the study, especially those resulting from the small number of patients in the group that received surgical treatment, which in turn led to the design of a larger, more sophisticated study. As is often the case, the data analysis cycle led to further research, and the process began anew. Evaluating a Research Study The six data analysis steps can also be used as a guide for evaluating published research studies. The following questions should be addressed as part of a study evaluation: What were the researchers trying to learn? What questions motivated their research? Was relevant information collected? Were the right things measured? Were the data collected in a sensible way? Were the data summarized in an appropriate way? Was an appropriate method of analysis used, given the type of data and how the data were collected? Are the conclusions drawn by the researchers supported by the data analysis? A. METHODS OF DATA COLLECTION Scientific inquiry generally starts with a hypothesis that a researcher wishes to investigate. This investigation requires the collection of data pertinent to the study. Data collection begins only after a research problem has been defined and research design finalized. A. METHODS OF DATA COLLECTION Types of Data Secondary Data Primary Data (Data already (Data collected for collected and passed the first time) through statistical process) A. METHODS OF DATA COLLECTION Primary data are collected for the first time, hence original in character. Secondary data are those which have already been collected by someone else and have already been passed through statistical process.  Methods of Collecting Primary Data Surveys Observation Experiments  Methods of Collecting Primary Data Surveys Observation Experiments Focus Personal Telephone Mailed On-line In-house self Group Interview Questionnaire administered Discussion Method (FGD) Schedules sent through Direct personal Indirect oral Enumerators interview Interview  Methods of Collecting Primary Data Surveys Observation Experiments Participant Non-participant Mechanical observation observation observation  Methods of Collecting Primary Data Surveys Observation Experiments Participant Non-participant Mechanical observation observation observation Participant observation The observer takes part in the situation he or she observes Mostly takes part in community settings  Methods of Collecting Primary Data Surveys Observation Experiments Participant Non-participant Mechanical observation observation observation Non-participant observation The observer does not participate in the situation Collects data by observing behavior without interacting with participants  Methods of Collecting Primary Data Surveys Observation Experiments Participant Non-participant Mechanical observation observation observation Mechanical observation People or situations are to be observed in a closed setting through mechanical devices  Methods of Collecting Primary Data Surveys Observation Experiments Experiments This is used when the objective is to find out the cause and effect relationship of certain phenomena under controlled conditions This method is usually employed by scientific researchers  Sources of Secondary Data Internal Sources External Sources Ministries, In house Agencies of govt publications Reports of international Bodies & foreign govt Letters, Records www., magazines Journals, newspapers Databases Associations Research groups and Companies Universities/Colleges Advantages and Disadvantages Types of Data Advantages Disadvantages 1. Less expensive 1. May not be 2. Easily applicable Secondary accessible 2. Potentially unreliable Data 3. Immediately 3. Frequently outdated available 1. Application and 1. Expensive usable 2. Not as readily Primary Data 2. Accurate and accessible reliable 3. Not available 3. Up-to-date immediately Ways by which data may be collected: 1. objective method requires the use of a measuring or counting instrument (meter stick, a weighing scale, a venier calliper, a color chart, or a counting device) one may collect data by objective means either by measurement or counting, or by observation Ways by which data may be collected: 2. subjective method relies on the information provided by identified respondents the instrument used to gather data usually comes in the form of a questionnaire one may collect data by conducting an interview (form of a personal interview or a telephone interview) or by gathering responses from mailed questionnaires Ways by which data may be collected: 3. use of existing records utilizing existing records data that are being collected have been previously collected by another person or institution for some other purpose (usually for administrative reasons) if the researcher’s inquiry requires the use of these data, he may collect and use them, properly acknowledging the source of the data. B. PLANNING AND CONDUCTING SURVEYS When you want somebody's opinion, you ask for it. That is easy enough when you are just dealing with one or a few people. But what if you want to know the opinion of an entire town or an entire population? Getting an answer out of everyone in your town or every member of a particular group is nearly impossible. B. PLANNING AND CONDUCTING SURVEYS So how do you get an idea of what these folks think? You use a survey. B. PLANNING AND CONDUCTING SURVEYS WHAT ARE SURVEYS? A survey is a way of collecting information that you hope represents the views of the whole community or group in which you are interested. B. PLANNING AND CONDUCTING SURVEYS Conducting surveys can be done very simply, or it can be very complicated, depending on how much you want to ask on the survey and the number of people to whom it is administered. This section will mainly focus on doing surveys on a fairly small local scale, and we will give you some ideas about where to find information should you need to do a survey on a larger scale. B. PLANNING AND CONDUCTING SURVEYS Three Main Ways 1. Case study surveys which collect information from a part of a group or community, without trying to choose them for overall representation of the larger population. You may need to conduct several of these before you get a sense of how the larger community would respond to your survey. Case study surveys only provide specific information about the community studied. B. PLANNING AND CONDUCTING SURVEYS Three Main Ways 2. Sampled surveys ask a sample portion of a group to answer your questions. If done well, the results for the sample will reflect the results you would have gotten by surveying the entire group. B. PLANNING AND CONDUCTING SURVEYS Three Main Ways 2. Sampled surveys For example, let say you want to know what percentage of people in your county would make use of an adult literacy program. Getting every person in a county with 10,000 people to fill out a survey would be a huge task. Instead you decide to survey a sample of 500 people and find out what they think. For the sample to accurately represent the larger group, it must be carefully chosen. B. PLANNING AND CONDUCTING SURVEYS Three Main Ways 3. Census surveys in which you give your survey questionnaire to every member of the population you want to learn about. This will give you the most accurate information about the group, but it may not be very practical for large groups. A census is best done with smaller groups -- all of the clients of a particular agency, for example, as opposed to all of the citizens of a city. B. PLANNING AND CONDUCTING SURVEYS Surveys are usually written, although sometimes the surveyor reads the questions aloud and writes down the answers for another person; they can be distributed by mail, fax, e-mail, through a web page, or the questions can be asked over the phone or in person. Surveys collect information in as uniform a manner as possible -- asking each respondent the same questions in the same way so as to insure that the answers are most influenced by the respondents' experiences, not due to how the interviewer words the questions. B. PLANNING AND CONDUCTING SURVEYS WHY SHOULD YOU CONDUCT A SURVEY? collect information about the behaviors, needs and opinions using surveys surveys can be used to find out attitudes and reactions, to measure client satisfaction, to gauge opinions about various issues, and to add credibility to your research surveys are a primary source of information -- that is, you directly ask someone for a response to a question, rather than using any secondary sources like written records B. PLANNING AND CONDUCTING SURVEYS WHY SHOULD YOU CONDUCT A SURVEY? You can use surveys to measure ideas or opinions about community issues related to your initiative. For example, you may want to know how many people use your services, what users think about your services, what new users expect from your services, and whether users are satisfied with what you provide. B. PLANNING AND CONDUCTING SURVEYS Deciding whether to conduct a survey You will need to decide whether a survey will produce the information you need. The information you need may be obtained through other means, such as informal unstructured conversation that takes place in the course of another activity; census figures; meeting with people in the community; interviews; or observation. B. PLANNING AND CONDUCTING SURVEYS Deciding whether to conduct a survey There are advantages in doing surveys, but you should consider whether a survey will be the best way of obtaining the information you need. Even though surveys are a useful method of gathering information, they are not the only way. B. PLANNING AND CONDUCTING SURVEYS WHEN SHOULD YOU CONDUCT A SURVEY? A SURVEY may be your BEST CHOICE when: You need a quick and efficient way of getting information You need to reach a large number of people You need statistically valid information about a large number of people The information you need isn't readily available through other means B. PLANNING AND CONDUCTING SURVEYS Written surveys: Pros and Cons Advantages of written surveys: Large numbers of people can Provides a written record give their input Easy to list or tabulate Low cost responses People can respond at their Wide range of respondents convenience No training needed as with Avoids interviewer bias interviewing B. PLANNING AND CONDUCTING SURVEYS Written surveys: Pros and Cons Disadvantages of written surveys: Often has low return rate May not truly represent of Limited alternative expression the whole group of respondent's reaction Respondent may skip sections Depends on the selected sample B. PLANNING AND CONDUCTING SURVEYS If you have decided that what you need is a large-scale, formal survey, hiring someone to do it for you or working with local colleagues or a nearby university may be your best bet. If you are going to do it on your own, keep in mind that some people you present your report to may not give much credit to a survey you did on your own. B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 1. Decide on the purpose of the survey 2. Decide whom you will survey 3. Decide what method you will use to collect survey data B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 1. Decide on the purpose of the survey If you have decided to do a survey, you must first be sure exactly why you are doing it. What questions do you want to answer? Is it to get a general idea of the demographics of your area? To find out what people think about a particular issue or idea? or Is there another reason you're considering a survey? B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 1. Decide on the purpose of the survey In any case, you will need to keep the purpose of the survey in mind throughout the process, as it will influence the choice of questions, the survey population, and even the way the survey is delivered (e.g., a computer-savvy population can be surveyed over the Internet; a population that is largely illiterate shouldn't be asked to take a written survey, and so forth) B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 2. Decide whom you will survey It is time for you to determine your audience -- the people who can best answer the questions your initiative needs to ask. ✓ Who will you survey? ✓ Is it the general public? ✓ The current program beneficiaries? ✓ People in a specific neighborhood or segment of the community? ✓ Potential members? B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 2. Decide whom you will survey Sampling Almost all surveys rely on sampling -- that is, identifying a section of your population that satisfies the characteristics you are trying to survey, rather than trying to do a census. B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 2. Decide whom you will survey Sampling To have a truly representative sample, you must be sure that every member of the group you want to survey has an equal chance of being in the sample, and/or you must have a fairly large sample. It is important to make sure that the sample size you choose is adequate and not excessively large or small. B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 2. Decide whom you will survey Sampling If too large, it may be impossible to survey everybody effectively and within your budget; if too small, your credibility may suffer. A general rule to keep in mind is that the larger the sample size, the more accurate a reflection of the whole it will be. You can figure out how big your sample should be by using a sample size calculator B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 2. Decide whom you will survey Sample Design Issues You might also need to give some thought to the design of your sample, especially if you are hoping to get representative responses from two or more groups. B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 2. Decide whom you will survey Sample Design Issues You might also need to give some thought to the design of your sample, especially if you are hoping to get representative responses from two or more groups. B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 2. Decide whom you will survey Sample Design Issues For example, let say you are doing a survey on youth violence and you want to get responses from youth, parents, and educators; this means that you will need to come up with separate population counts for each of these groups and then select a sample from each. The samples should be large enough to represent the group it is drawn from, but the sample sizes should be proportional to the groups they represent. Youth Parents Educators Population 650 200 500 Sample 65 20 50 B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 2. Decide whom you will survey Potential pitfalls Sampling is a challenge to conducting good surveys, but there are other pitfalls. For example, when people volunteer to respond to a survey, we say they are self-selected. These people may have a special interest in answering your survey, so their answers may not be truly representative of the group you are interested in. There are ways of dealing with self-selected audiences, such as only using a random selection of their surveys when only self- selection is involved. B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 3. Decide what method you will use to collect survey data Will your survey be written or oral? Is there going to be a number where people can call to register their results? Are you going to have a post office box to which completed surveys should be mailed? B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 3. Decide what method you will use to collect survey data You need to decide whether it is going to be administered by people known to the audience and whether it will be done in person, by phone, or by mail. Remember that the more personal you make it, the higher the return rate will be. Surveys that are delivered cold have a return rate of only two to three percent, unless they are on a very hot topic for the community you are surveying. B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 3. Decide what method you will use to collect survey data Keep in mind whom you want to survey. Does your public feel more comfortable in writing or speaking? Will it be efficient to leave surveys somewhere for people to pick up at their will, or should you do something to make sure they get one? If your survey is to be administered orally, will people feel honored or annoyed about being asked for their opinions? B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU PREPARE A SURVEY? 3. Decide what method you will use to collect survey data Mailed questionnaires are a very useful tool in your information-gathering bag of tools. It is a much cheaper alternative to other types of information gathering and it allows you to get information from many people across long distances without paying extremely high phone bills. If you're considering doing a mailed survey, be sure to check with your local post office for information on mailing regulations, bulk mail rates, and so on. B. PLANNING AND CONDUCTING SURVEYS Advantages of mailed questionnaires The respondent can fill out the survey at his or her convenience -- it can be filled out whenever the respondent has time. You can make it anonymous, which is much more comfortable for some respondents. All respondents will have read the same questions, eliminating any interviewer bias. The respondent will have time to check his or her records before answering -- if he or she needs to verify information, he or she will have the chance to be accurate. B. PLANNING AND CONDUCTING SURVEYS Disadvantages of mailed questionnaires They are not very flexible; there is no interviewer present to probe for answers, so you can only read what the respondent has written, with no opportunity to look at facial expressions or body language. The return rate is generally low Respondents may leave answers blank You can't control when respondents will send the survey back You may not be able to tell the difference between those who simply didn't return the survey and those for whom you had an incorrect address. B. PLANNING AND CONDUCTING SURVEYS WRITE YOUR QUESTIONS When Preparing the questions, bear in mind that they can take many forms. Questions might be: 1. Open-ended o Designed to prompt the respondent to provide you with more than just one or two word responses. o These are often "how" or "why" questions. B. PLANNING AND CONDUCTING SURVEYS WRITE YOUR QUESTIONS When Preparing the questions, bear in mind that they can take many forms. Questions might be: 2. Closed-ended o also sometimes referred to as forced choice questions o specific questions that prompt yes or no answers. B. PLANNING AND CONDUCTING SURVEYS WRITE YOUR QUESTIONS When Preparing the questions, bear in mind that they can take many forms. Questions might be: 3. Multiple choice o allow the respondent to select one answer from a few possible choices B. PLANNING AND CONDUCTING SURVEYS WRITE YOUR QUESTIONS When Preparing the questions, bear in mind that they can take many forms. Questions might be: 4. Likert scale o each respondent is asked to rate items on a response scale. For instance, they could rate each item on a 1-to-5 response scale where: 1 = strongly disagree 2 = disagree 3 = undecided 4 = agree 5 = strongly agree B. PLANNING AND CONDUCTING SURVEYS Guidelines for writing your survey questions Place easier questions first Address sensitive issues as discreetly and sensitively as possible Avoid words that provoke bias or emotional responses Use a logical order and place similar questions together B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU DISTRIBUTE YOUR SURVEY? There are several strategies for distributing surveys. You may want to use a combination of methods. Methods of Distribution 1. Direct Mail Direct mailing your survey to people whose addresses are known is the most common strategy. Distributing a survey by mail has a high percentage of non- responders (you are lucky if 30% respond, although it tends to be higher in small communities), but it is a lot easier than many other methods and takes less staff hours. B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU DISTRIBUTE YOUR SURVEY? Methods of Distribution 2. Interviews and Phone Surveys For those who have difficulty reading or using printed materials, or for surveys that require more in-depth answers, interviews might be the most appropriate thing for you to do. Phone surveys work similarly to face-to-face interviews, so we have grouped these two methods together B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU DISTRIBUTE YOUR SURVEY? Methods of Distribution 3. Drop Boxes It can also be a good way to contact clients of other agencies who have little contact with your group or agency. However, if you use this method of distributing surveys, consider using it along with at least one other method of distribution, because only those already using the services can respond. B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU DISTRIBUTE YOUR SURVEY? Methods of Distribution 4. Media Distribution For general distribution, publishing a survey in the local paper or attaching a survey to your newsletter might be a good idea B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU DISTRIBUTE YOUR SURVEY? Methods of Distribution 5. Convenience Sampling Taking surveys in a public place -- setting up a booth or table in the parking lot at a local discount store, on the sidewalk in the shopping district, etc. -- provides an opportunity to get some exposure for your organization. B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU DISTRIBUTE YOUR SURVEY? Methods of Distribution 6. Group Administration If your group or organization tends to have large group gatherings, providing surveys to everyone who attends a particular gathering might be a really efficient way for you to gather information. B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU DISTRIBUTE YOUR SURVEY? Methods of Distribution 6. Group Administration If you want to give your survey out at some sort of group meeting or gathering, get the group's director to put you on the agenda. At the meeting, introduce yourself and explain the purpose of the survey. Then distribute the survey, answer any questions, and collect completed surveys. Don't forget to thank everyone for their participation! B. PLANNING AND CONDUCTING SURVEYS HOW DO YOU DISTRIBUTE YOUR SURVEY? Methods of Distribution 7. Using Multiple Methods of Distribution You can combine or adapt two or more of the above methods to suit your own purposes. If more than one method is used, each survey should include instructions that each citizen should complete only one survey. Example Clio wants to construct a survey that shows which university students at her school (SHS) likes to study at in college and what are their preferred courses. C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Experiment – a test or a series of tests in which purposeful changes are made to the input variables or factors of a system so that we may observe and identify the reasons for changes in the output response(s) C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Experiments are used to study the performance of processes and systems Figure 1. General model of a process or system C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS We can usually visualize the process as a combination of operations, machines, methods, people, and other resources that transforms some input (often a material) into an output that has one or more observable response variables. Figure 1. General model of a process or system C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Some of the process variables and material properties x1, x2,... , xp are controllable, whereas other variables z1, z2,... , zq are uncontrollable (although they may be controllable for purposes of a test). Figure 1. General model of a process or system C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS The objectives of the experiment may include: 1. Determining which variables are most influential on y 2. Determining where to set the influential x’s so that y is almost always near the desired nominal value variability in y is small the effects of z1; … ; zq are minimized C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Experiments often involve several factors The golf experiment all possible combinations of factor levels are tested Type of driver Time of round Type of ball Weather Walking vs. riding Type of golf spike Type of beverage C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Strategy of Experimentation – it is the general approach to planning and conducting the experiment Strategy of Experimentation 1. best-guest approach 2. one-factor-at-a-time(OFAT) approach 3. factorial experiment C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Strategy of Experimentation 1. best-guest approach (trial and error) frequently used in practice often works reasonably well often have great deal of technical or theoretical knowledge of the system disadvantage: spend time to guess the initial best-guess no guarantee that the best solution has been found C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Strategy of Experimentation 2. one-factor-at-a-time(OFAT) approach used extensively in practice disadvantages: inefficient (requires many test runs) fails to consider any possible interaction between factors C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Strategy of Experimentation 3. factorial experiment which factors are varied together extremely important correct, modern, and most efficient approach all possible combinations of the factors across their levels are used in the design enable to investigate the individual effects of each factor and to determine whether the factors interact C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Statistical Design of Experiment (DOE) – the process of planning experiments so that appropriate data will be collected and analyzed by statistical methods that results in valid, objective, and meaningful conclusions from the data – involves two aspects: design and statistical analysis C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Every experiment involves a sequence of activities: o Conjecture - hypothesis that motivates the experiment o Experiment - the test performed to investigate the conjecture o Analysis - the statistical analysis of the data from the experiment o Conclusion - what has been learned about the original conjecture from the experiment. C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Three Basic Principles of Statistical DOE 1. Replication - an independent repeat run of each factor combination allows an estimate of experimental error allows for a more precise estimate of the sample mean value 2. Randomization – is running the trials in random order cornerstone of all statistical methods “average out” effects of extraneous factors reduce bias and systematic errors C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Three Basic Principles of Statistical DOE 3. Blocking – a design technique used to improve the precision with which comparisons among the factors of interest are made increases precision of experiment “factor out” variable not studied C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Guidelines for Designing an Experiment 1. Recognition of and statement of the problem (Pre-experimental planning) need to develop all ideas about the objectives of the experiment 2. Choice of factors, levels, ranges and response variable (Pre- experimental planning) Need to use engineering judgment or prior test results Controllable; Uncontrollable; noise factors; cause-and-effect diagram C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Guidelines for Designing an Experiment 3. Choice of experimental design sample size, replicates, run order, randomization, software to use, design of data collection forms 4. Performing the experiment vital to monitor the process carefully. Easy to underestimate logistical and planning aspects in a complex R and D environment C. PLANNING AND CONDUCTING EXPERIMENTS: INTRODUCTION TO DESIGN OF EXPERIMENTS Guidelines for Designing an Experiment 5. Statistical analysis of the data provides objective conclusions use simple graphics whenever possible graphical methods; empirical model 6. Conclusions and recommendations follow-up test runs and confirmation testing to validate the conclusions from the experiment Get in Touch With Us Send us a message or visit us City of Batac, Ilocos Norte, Philippines (63) 77-600-0459 [email protected] Follow us for updates facebook.com/MMSUofficial www.mmsu.edu.ph