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• Math 50 - Engineering Data Analysis, Unit 1 is about obtaining data
• Engr. Roxanne Joy O. Antonio wrote the text at Mariano Marcos State University, College of Engineering, Department of Agricultural and Biosystems Engineering

Objectives

• Students should be able to discuss terms related to data analysis
• Students should be able to classify data as qualitative or quantitative
• Students should be able to classify variables as discrete or continuous
• Students should be able to discuss how measurements or data are generated
• Students should be able to describe data and how they are used for making engineering decisions
• Students should be able to demonstrate an understanding of the different methods of obtaining data
• Students should be able to explain the procedures in planning and conducting surveys and experiments

What Engineers Do

• Engineers solve problems of interest to society with the efficient application of scientific principles by:
  • Refining existing products
  • Designing new products or processes

The Engineering Method

• Steps includes:
  • Develop a clear description
  • Identify the important factors
  • Propose or refine a model
  • Manipulate the model
  • Confirm the solution
  • Conclusions and recommendations
  • Conduct experiments

Data

• Data are facts, figures, and information collected on some characteristics of a population or sample
• These can be classified as qualitative or quantitative data
• Data are factual information (as measurements or statistics) used as a basis for reasoning, discussion, or calculation
• Data arw 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

• Statistics deals with the collection, presentation, analysis and use of data to make decisions, solve problems, and design products and processes
• Statistics involves learning from data, and of measuring, controlling, and communicating uncertainty; and it thereby provides the navigation essential for controlling the course of scientific and societal advances

3 Reasons to Study Statistics

• Being informed is the first reason to study statistics
  • 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
  • Kids were cited as the biggest offenders
  • As evidence, the author cited a 2004 study by Public Agenda
  • The 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
• Making informed judgements
• Evaluating decisions that affect your life:
  • Other people will use statistical methods to make decisions that affect you as an individual

Statistical Terms

• Population
• Sample
• Data
• Ungrouped data
• Grouped Data
• Parameter
• Statistic
• Constant
• Variable

Example

• Aim: To determine if all Females over 30 years old in Batac City can lose weight is they use a Vegan diet?

Descriptive Statistics

• Deals with procedures that organize, summarize and describe quantitative data
  • Seeks merely to describe data
• Common tools include
  • 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 and 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 include
  • Hypothesis Testing
  • Regression Analysis
• Example:
  • 20% living in the subdivision prefer to drive Toyota cars

The Data Analysis Process

• Understanding the nature of the problem
• Deciding what to measure and how to measure it
• Data collection
• Data summarization and preliminary analysis
• Formal data analysis
• 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 who received the standard care for Alzheimer's disease
• After analyzing the data, 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 and 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 analysis was used, the investigators reached the conclusion that the surgical procedure showed promise
• 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

• Use the six data analysis steps as a guide for evaluating published research studies
  • 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?

Methods of Data Collection

• Scientific inquiry generally starts with a hypothesis that a researcher wishes to investigate
• The 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

Types of Data

• 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
  • Personal Interviews
  • Telephone Interviews
  • Mailed Questionnaire Method
    • Schedules sent through Enumerators
  • On-line
  • In-house self administered
  • Focus Group Discussion (FGD)
  • Direct personal interview
  • Indirect oral Interview
• Observation
  • Participant observation, where the observer takes part in the situation he or she observes
    • This mostly takes part in community settings
  • Non-participant observation, where observer does not participate in the situation
    • The collector collects data by observing behavior without interacting with participants
  • Mechanical observation, where people or situations are to be observed in a closed setting through mechanical devices
• Experiments
  • 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

Advantages and Disadvantages

Ways By Which Data May Be Collected

• Objective method:
  • Requires the use of a measuring or counting instrument (meter stick, a weighing scale, a vernier calliper, a color chart, or a counting device)
  • One may collect data by objective means either by measurement or counting, or by observation
• Subjective method:
  • Relies on the information provided by identified respondents
  • The instrument used to gather data usually comes in the form of a questionnaire
  • Collect data by conducting an interview (form of a personal interview or a telephone interview) or by gathering responses from mailed questionnaires
• Using existing records:
  • Utilizing existing records
  • The data 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 those data, he may collect and use them, properly acknowledging the source of the data

Planning and Conducting Surveys

• When you want someone’s opinion, you ask for it
  • This seems easy enough, you may be thinking, 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 obviously impossible
  • So how do you get an idea of what these folks are thinking? You use a survey
• 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
• 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 Three Main Ways
• Case study surveys
  • 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
• Sampled surveys
  • Asks 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
  • For example, if 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 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
• Census surveys
  • 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

Important Factors about Surveys

• Surveys are usually written, although sometimes the surveyor reads the questions aloud and writes down the answers for another person
• Can be distributed in various ways:
  • Mail, fax, e-mail, through a web page, or the questions can be asked over the phone or in person
• They 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

Why Should You Conduct A Survey

• Collect information about the behaviors, needs and opinions using surveys
• Can be used to find out attitudes and reactions
  • Measure client satisfaction
  • Gauge opinions about various issues and to add credibility to your research
• They are a primary source of information
  • You directly ask someone for a response to a question, rather than using any secondary sources like written records
• 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

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
  • Informal unstructured conversation that takes place in the course of another activity
  • Census figures
  • Meeting with people in the community; interviews; or observation
• There are advantages in using surveys
  • Consider whether a survey will be the best way of obtaining the information you need
    • They are a useful method of gathering information, but they are not the only way -A SURVEY may be your BEST CHOICE when:
  • 1. You need a quick and efficient way of getting information
  • 2. You need to reach a large number of people
  • 3. You need statistically valid information about a large number of people
  • 4. The information you need isn't readily available through other means

Written surveys: Pro and Cons

• 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

How Do You Prepare A Survey

• 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? 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
  • 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
• 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?
  • Sampling
  • Almost all surveys rely on sampling - identifying a section of your population that satisfies the characteristics you are trying to survey, rather than trying to do a census
• Decide what method you will use to collect survey data
  • With sampling, 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
  • If too large, it may be impossible to survey everybody effectively and within your budget
  • if too small, your credibility may suffer
  • You can figure out how big your sample should be by using a sample size calculator
• 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
  • If 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
    • Select a sample from a sample from each
• Make they large enough samples:
  • Should be large enough to represent the group it is drawn from
  • The sample sizes should be proportional to the groups they represent

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, 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:
  • Only use random selection of their surveys when only self- selection is involved

Decide What Method Will Be Used To Collect Survey Data

• Will the 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?

Key Aspects in Method Selection

• Think about who will use the survey
• Consider if your audience is writing or speaking people
• Will it be efficient if left somewhere at will or will people be encouraged?
• Is it going to administered orally? Will people feel honoured or annoyed for being asked for their opinions?
• 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, and that 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

Mailed questionnaires are a useful tool

• It is a much cheaper alternative to other types of information gathering
• Allows to aquire information from 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, etc.
• 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
• 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
  • 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

Guidelines for Writing Your Survey Questions

When preparing your questions, take the time take into account the many forms your questions can take

• Open-ended: these are questions designed to promote the respondent to give a response, rather than a yes or no answer. Typically these begin with "how or why"
• Closed-ended: these questions are forced and are more specific questions that need basic "yes or no" answers
• Multiple-choice: questions that allow a respondent to pick one answer from a few possible options
• Likert scale: prompts an opinion on a scale
• 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

Methods of Distribution

• Direct Mail
  • Send surveys directly to people who addresses are known, this is the most common strategy
• Interviews and Phone Surveys
  • Suited if individual have complications when reading or in-depth information may be required
  • Phone surveys have the same effect as a face-to-face interview
• Drop Boxes
• A good way to contact clients of other agencies who have little contact with your agency
• Should be used with another method, to prevent drop boxes being limited to those using the same service already
• Media Distribution
  • Publish papers or attach to news letters can be used to conduct a survey
• Convenience Sampling
  • Conduct the survey in a public place to gain exposure of the study
• Group Administration
  • Is you are doing an analysis to gain gathering with a group
    • In the meeting describe why your survey is is important
    • Send out the survey while answering any questions - Thank everyone by there completion

How Do You Distribute Your Survey

• There are several strategies for distribution
  • Might be good to uses a mixture of methods

Example

• Clio wants to construct a survey that indicates what school is preferred by university students as well as preferred courses

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)
• Experiments are used to study the performance of processes and systems
• 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
• Objectives of the experiment may include:
  • Determining which variables are most influential on y
  • 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
• Examples of factors and their all possible combinations:
  • Type of driver
  • Type of ball
  • Walking vs. riding
  • Time of round
  • Type of beverage
    • Weather
      • Golf spike

Strategy of Experimentation

• Strategy of Experimentation is the general approach to planning and conducting the experiment:
  • best-guest approach
  • one-factor-at-a-time(OFAT) approach • factoral experiment
• 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 best guess, and no guarantee the best could be found
    • used extensively in practice ✓inefficient (requires many test runs) ✓fails to consider any possible interaction between factors • Factorial experiment: Factors which are varies together to make sure all the are as correct can is efferent

Three Basic Principles of Statistical DOE

• Replication is an independent run of run which involves a factor
  • Allows an estimate of experimental error as well as to the mean value
    • Is running the trials in random order corner stone of all statistics
      • Effected through out random factors
        • To reduce BIAS

Design Techniques

• Design techniques used to improve between all technique include the following: -Increase Variable not studied Guidelines for Designing an Experiment
• Recognition of and statement of the problem (Pre-experimental planning)
• Need engineering judgement prior test result - Pre Experimental need knowledge as well Objectives of the experiment

In order

• In order to perform monitor process and understand logistically must be designed with other information - Vital objective must is done in simple graphics

Every experimental

• Every experimentation must follow the following information

1. • Conjectures: An hypothesis for an experimentation 2 . Experiment: Is the test to preformed and have results a : An is analysis in analysis the that a staical must can all
2. Be analysis can perform -Conclusion: Is it the final test being presented has to be reviewed