1. Chapter 2 The Data Analysis Process and Collecting Data Sensibly
What is the basis of a study?

2. 2-1
How is data classified?

3. Variable—any characteristic that may change
Data—results from observing variables
Univariate data—has one variable
Bivariate data—has two variables
Multivariate data—has two or more variables
Categorical data—(qualitative)—has responses that are types not numbers
Numerical data—(quantative)—has responses that are numbers
Discrete data—individual points—integer values
Continuous data—a continuum of data—real number values

4. Summarization
What type a data would the solution set be? discrete or continuous 1. There are 30 spots on a ferry to park vehicles. A car takes one spot and a bus takes 3 spots. What type a data would the solution set be? 2. The fuel efficiency of a new car.

5. Homework
Pg & 2.2

6. What is the data analysis process?
2-2
What is the data analysis process?

7. Planning and Conducting a Study
Understand the nature of the problem
Know the goal and what questions must be answered
Decide What to measure and How to measure it
Carefully define the variables and an appropriate means of determining these values
Data Collection
Decide if an existing source will work or if new data should be collected
Determine any limitations of your collection methods
Data Summarization
Both graphical and numerical
Formal Analysis
Apply appropriate methods
Interpretation of Results
Draw conclusions and answer the question

8. Questions to ask of a research project:
What were the researchers trying to learn?
Was relevant information collected?
Was it collected in a sensible way?
Was it analyzed appropriately?
Are the conclusions supported by the research?

9. What is the difference between observation and experimentation?
2-3
What is the difference between observation and experimentation?

10. Observational Study—looking at existing characteristics of an existing population and drawing a conclusion
Experimental—if the researcher manipulates one or more factors to determine how a response variable behaves
Must obtain a sample that represents the corresponding population
Cannot draw cause and effect relationship
The researcher controls who is in which group and applies a “treatment” on at least one group

11. Confounding Variable—one that is related to both group membership and the response variable
Example
Researchers determined that students who have a larger vocabulary have more cavities.
Is there a confounding variable or is there a causal relationship
age

12. Summarization
Which of the following statements about experiments are true?
a) all experiments must have a control group
b) blocking is employed to reduce variation
c) Random assignment is only critical for treatment groups as opposed to control groups
d) matching can be used in any experiment to eliminate lurking variables
e) none of these is true. b
1-B

13. Homework
Pg , 2.6, 2.7, 2.8, 2.9

14. What considerations need to be made in sampling?
2-4
What considerations need to be made in sampling?

15. Sampling Why would you use a sample over a population?
Limited resources—time and money
Destructive measurement—when the items to be studied requires using up the population
Breaking strength of a soda bottle
The life of a battery

16. Types of Sampling
Random—when all the items have an equal chance of being chosen to be in the sample
Convenience—doesn’t take into account all the factors that may be in the population
Just an easy group to gather
Stratified sample—the group is broken into subgroups and then a random sample is chosen from each subgroup
By age
By distance
Cluster sample—natural grouping are evident in the population to be studied
Need to find out how all university students feel on a topic take a random sample from each university
Zip codes
Counties
Systematic—choosing the nth item in the population
Every 5th person who walks into the cafeteria

17. Types of Sampling
With replacement—the same item can be used over in the sample
Without replacement—the same item may only be used once in the sample

18. Sample Frame
Create a sampling frame—a list of all eligible items in the population identified by a number
Generate a list of random numbers and then use items for your sample

19. Types of Bias
Start at 8:40
Selection—when a part of the population is excluded from the study because of design
Measurement (numeric) or Response —tends to produce values that differ from the population due to the way something is measured or stated
Non-response—when members of the population who were asked for the opinion do not respond

20. Example:

21. Summarization
1. A marketing company offers to pay $25 to the first 100 persons who respond to their advertisement and complete a questionnaire regarding displays of their client’s product. This situation is an example of which of the following? a) simple random sample (SRS) b) convenience sample c) voluntary response sample d) multistage cluster sample e) None of the above 2. A simple random sample was selected of large urban school districts throughout New England. The selected districts were identified as target districts. Within each district, a SRS of its high schools were chosen and their principals interviewed. Which of the following is not true? a) This is an example of a multi-stage cluster sample b) Results from the interviews cannot be used to infer responses to the population of interest c) The population of interest is the set of all high school principals from large urban school districts in New England d) Not every subset of principals has the same chance of selection e) all are true
1-C 2-B

22. Homework:
Pg and 2.12

23. What is a comparative experiment?
2-5
What is a comparative experiment?

24. Simple Comparative Experiment
When the value of some response variable is recorded some method is implemented and the new response is recorded

25. Experiment—a planned intervention
Variables—factors that can be manipulated
Experimental condition or treatment—that which is done to the variable
Design—the overall plan
Extraneous variables--variables other than the independent variable that may bear any effect on the behavior of the subject being studied but not felt to confound the results

26. Fundamental Principles of Design
Control—removing extraneous factors
Blocking—creating groups that are similar by removing confounding variables by sharing them among groups
Randomization—ensuring equality of groups
Replication—repetition of an experiment or observation in the same or similar conditions

27. Control Group—a group that receives no treatment
Blind Study—subjects don’t know which treatment they are getting
Double blind Study—the observer and the subjects do not know who is getting which treatment (only the experimental designer knows)
Placebo—something given that has no effect but doesn’t allow the person to know if they are getting the treatment or the placebo

28. Blocking experiment

29. Summarization
1. Blocking is utilized to help a) organize the treatment and control groups b) counteract the placebo effect c) produce groups that are as similar as possible d) replicate the experiment within each block e) avoid the need for randomization 2. If the director selects 50 employees at random from throughout the company and categorizes their lunchtime by gender, she is: a) blocking on gender b) testing for a lurking variable c) promoting sexual harassment d) testing for bias e) none of these
1-C 2-B

30. Homework
Pg and 2.30