1. Course Content Introduction to the Research Process
Identification of the Research Problem
Development of the Research Question or Hypothesis
Formulation of the Research Methods
Analysis and Interpretation of the Collected Data
Writing the Research Report

2. The Scientific Method Develop the problem
Develop a theoretical solution to the problem
Formulate the hypothesis or question
Formulate the research plan (methods)
Collect and analyze the data
Interpret the results and form conclusions
Refine the theory
Developing the problem
Why do you want to observe?
Formulating the hypothesis or question
Whom & what do you want to observe?
Hypothesis – expected result
Based on theoretical construct, results of previous studies, or past experiences or observations
Hypothesis should be testable, not a value judgment or unobservable abstract phenomenon
Gathering the data
How and when do you want to observe?
Decide on proper methods to acquire data (very difficult)
Reliability and validity of measuring instruments
Employment of controls
Objectivity and precision of data gathering process
Maximize internal and external validity
External validity – generalizability of results
Internal validity – extent to which results can be attributed to treatments used (EVs)
Gather data (easy part)
Analyzing and interpreting the results
Most formidable step
Typically use inductive reasoning (synthesize data from his/her study with results of other studies) to contribute to development or substantiation of a theory
Review study from pp in Baumgartner & Strong

3. Formulation of the Research Methods
Selecting the Appropriate Design
Selecting the Subjects
Selecting Measurement Methods & Techniques
Selecting Instrumentation

4. Formulation of the Research Methods
Developing Procedures & Protocol
Using a Pilot Study
Selecting the Appropriate Analysis Techniques
Developing a Timeline & Budget
Collecting the Data
We will talk about each of these in more detail as we go through the semester. The purpose of this lecture is to simply provide an overview of the steps that need to be taken. Although, we will discuss selection of subjects in much detail tonight. The other three topics will be discussed in more detail later.

5. Sampling Procedures

6. Definitions
Population – group of things (people) having one or more common characteristics
Sample – representative subgroup of the larger population
Used to estimate something about a population (generalize)
Must be similar to population on characteristic being investigated
Sample should be large & randomly drawn
Random sampling
ensures representativeness for generalizability
shows researcher was unbiased as to selection
equalizes characteristics among groups at the beginning
Large sample
ensures reliability
allows attrition

7. Representative

8. Non-Probability Sampling
Sampling Methods
Probability Sampling
Simple random sampling
Stratified random sampling
Systematic sampling
Cluster (area) sampling
Multistage sampling
Non-Probability Sampling
Deliberate (quota) sampling
Convenience sampling
Purposive sampling

9. Simple Random Sampling
Equal probability
Techniques
Fishbowl (with replacement & w/o replacement)
Table of random numbers
Advantage
Most representative group
Disadvantage
Difficult to identify every member of a population
Sometimes difficult or impossible to identify every member of the population.
Inferences biased to some degree away from the characteristics of those missing portions of the sample.

10. Stratified Random Sampling
Technique
Divide population into various strata
Randomly sample within each strata
Sample from each strata should be proportional
Advantage
Better in achieving representativeness on control variable
Disadvantage
Difficult to pick appropriate strata
Difficult to ID every member in population
Divide population into various strata (subgroups) based on some characteristic that is important to study
Select a set # from each strata
Number of subjects from each strata should represent the proportion of that subgroup in the total population

11. Systematic Sampling Technique Advantage Disadvantage
Use “system” to select sample (e.g., every 5th item in alphabetized list, every 10th name in phone book)
Advantage
Quick, efficient, saves time and energy
Disadvantage
Not entirely bias free; each item does not have equal chance to be selected
System for selecting subjects may introduce systematic error
Cannot generalize beyond pop actually sampled
A sample obtained by determining the sample interval, selecting a random starting point between 1 and k, and then selecting every kth element
Non-random
Shopping Mall example – location in mall may still bias sample
1936 election
EX of error:
Use of phone book – those who don’t have phones
Intramural basketball
Pass by store in mall – all stores in this area are stores for women’s clothing

12. Cluster (Area) Sampling
Randomly select groups (cluster) – all members of groups are subjects
Appropriate when
you can’t obtain a list of the members of the population
have little knowledge of pop characteristics
Pop is scattered over large geographic area
EXAMPLE
You want 1000 teachers out of population of 4600 teachers in 46 schools in a city (100 teachers per school). Problem is that a true random sample would have you all over the place. Randomly choose 12 schools (clusters) and sample all 100 teachers in each school selected.
Randomly select football teams from DII.
Bias in the selection of clusters will tend to be magnified in its effect on the outcome of the study.

13. Cluster (Area) Sampling
Advantage
More practical, less costly
Conclusions should be stated in terms of cluster (sample unit – school)
Sample size is # of clusters
EXAMPLE
You want 1000 teachers out of population of 4600 teachers in 46 schools in a city (100 teachers per school). Problem is that a true random sample would have you all over the place. Randomly choose 12 schools (clusters) and sample all 100 teachers in each school selected.
Randomly select football teams from DII.
Bias in the selection of clusters will tend to be magnified in its effect on the outcome of the study.

14. Multistage Sampling Stage 1 Stage 2 randomly sample clusters (schools)
randomly sample individuals from the schools selected

15. Non-Probability Sampling
Sampling Methods
Probability Sampling
Simple random sampling
Stratified random sampling
Systematic sampling
Cluster (area) sampling
Multistage sampling
Non-Probability Sampling
Deliberate (quota) sampling
Convenience sampling
Purposive sampling

16. Deliberate (Quota) Sampling
Similar to stratified random sampling
Technique
Quotas set using some characteristic of the population thought to be relevant
Subjects selected non-randomly to meet quotas (usu. convenience sampling)
Disadvantage
selection bias
Cannot set quotas for all characteristics important to study
Sample is biased; researcher is free to select subjects as he or she sees fit.
Difficult to set quotas for all of the demographic and other characteristics that may be relevant to the outcome of the study (views toward abortion may be affected by gender, parental status, religion, economic status, education, political affiliation, race, family history, and many other factors
only use when research advantages are superior to statistical and public relations aspects of bias-free selection

17. Convenience Sampling “Take them where you find them” - nonrandom
Intact classes, volunteers, survey respondents (low return), a typical group, a typical person
Disadvantage: Selection bias
Use post hoc analysis to show groups were equal at the start
Must describe in detail the characteristics of the people participating
Show groups were equal at the start (post hoc analysis) – better than nothing, but not as good as random sampling; still don’t know if groups differ on some unmeasured characteristic

18. Purposive Sampling Purposive sampling (criterion-based sampling)
Establish criteria necessary for being included in study and find sample to meet criteria
Solution: Screening
Use random sampling to obtain a representative sample of larger population and then those subjects that are not members of the desired population are screened or filtered out
EX: want to study smokers but can’t identify all smokers

19. Sample Size Critical factor is whether sample is representative
Necessary sample size depends on population size
Recommendations:
Use tables from books
30 per group
Descriptive studies – 10-20% of population
No more than 50% of population
Statistical power
Attrition
When selecting sample size, consider
selection process (random or not) – most important for generalizability
types of variables studied
how data are collected
statistical procedures
public relations
Experimental studies use less subjects than descriptive because attrition usually less; nonresponse in questionnaire studies important

20. Other Sampling Considerations
Random assignment
Sampling of treatments (experimental research)
Use post hoc analysis to show groups were equal at the start
Since random sampling is often impossible, sample must be selected on some theoretical basis
Be careful with generalizations

21. When Selecting Subjects …
Are subjects with special characteristics necessary for your research? (age, gender, trained/untrained, expert/novice, size, etc.)
Can you obtain the necessary permission and cooperation from the subjects?
Can you find enough subjects?
Interaction among selection of subjects, treatments, and measures is essential for experimental studies.
Examples of interactions to be considered:
Subjects with high level of fitness will not respond to moderate training program.
Subjects with high physical fitness will have small range of scores (homogeneous) on VO2 max, and will have poor correlation between VO2max and endurance performance.
Does not mean that there is no relationship, but rather you have restricted range of performance so much that correlation can not be exhibited.
We will now discuss various techniques used to select samples of subjects.

22. Reporting Subjects State how many subjects were selected
Describe how the subjects were selected
Discuss whether any subjects were lost during the study and why
Explain why the subjects were selected
Describe subject characteristics that are pertinent to study – be very specific
Identify procedures taken to protect the subjects
Identify procedures taken to protect the subjects
This may vary from study to study
It is usually sufficient to state that informed consent was obtained, but where there were substantial risks to the subjects, the precautionary steps should be explained