Assignment 5

Sampling Techniques, Validity, and Reliability

Objectives

Upon completion of this assignment, you will be able to:

1. Explain the concept of random sampling.
2. Show an understanding of stratified random sampling and explain the conditions under which it would be used.
3. Show an understanding of large and small samples and explain their advantages and limitations.
4. Explain the limitations of using volunteers in a sample.
5. Define validity.
6. Explain and give an example of
   1. construct validity,
   2. content validity, and
   3. criterion-related validity.
7. Describe the consequences resulting from the lack of internal validity in a study.
8. Describe the consequences resulting from a lack of external validity in a study.
9. Explain why several variables pose a threat to internal validity.
10. Explain why several variables pose a threat to external validity.
11. Define the concept of reliability.
12. List and explain the following types of reliability coefficients:
    1. test-retest,
    2. parallel form, and
    3. internal consistency.

Reading Assignment

• Pyrczak and Bruce, pp. 79-90 (6th edition); 79-90 (7th and 8th editions) 
• Lang and Heiss, pp. 95-97, 44-48, 93-95, and 48-52.
• Isaac and Michael, pp. 66-70, 128-133, 134-136, and 201.
• Tuckman, pp. 237-241, 262-263, 160-161, 6-7, 182-184, 6-10, 121-126, 126-128, and 180-182.

Evaluation

Successful completion of this assignment can be accomplished by answering the following questions in typed format.

1. Explain the concept of random sampling.

2. Define stratified random sampling and explain the conditions under which it should be used.

3. Explain the advantages and limitations of large and small samples.

4. What are the limitations of using volunteers in a sample.

5. Define validity.

6. Explain and provide an example of
   1. construct validity,
   2. content validity, and
   3. criterion-related validity.

7. Define internal and external validity.

8. Explain the consequences resulting from a lack of internal validity.

9. Explain the consequences resulting from a lack of external validity.

10. What are several variables that pose a threat to internal validity.

11. What are several variables that pose a threat to external validity.

12. Define the concept of reliability.

13. List and explain the following types of reliability coefficients:
    1. test-retest,
    2. parallel form,
    3. internal consistency.