Problem Set 3.1: Sampling Distribution of the Mean Exercise

Criterion: Interpret population mean and variance.

Instructions: Read the information below and answer the questions.

Suppose a researcher wants to learn more about the mean attention span of individuals in some hypothetical population. The researcher cites that the attention span (the time in minutes attending to some task) in this population is normally distributed with the following characteristics: 20 36 . Based on the parameters given in this example, answer the following questions:

1.What is the population mean ()? ____20_______________

2.What is the population variance ? __6______________________

3.Sketch the distribution of this population. Make sure you draw the shape of the distribution and include the mean plus and minus three standard deviations.

Problem Set 3.2: Effect Size and Power

Criterion: Explain effect size and power.

Instructions: Read each of the following three scenarios and answer the questions.

1.Two researchers make a test concerning the effectiveness of a drug use treatment. Researcher A determines that the effect size in the population of males is d = 0.36; Researcher B determines that the effect size in the population of females is d = 0.20. All other things being equal, which researcher has more power to detect an effect? Explain. ______________________________________________________________________

2.Two researchers make a test concerning the levels of marital satisfaction among military families. Researcher A collects a sample of 22 married couples (n = 22); Researcher B collects a sample of 40 married couples (n = 40). All other things being equal, which researcher has more power to detect an effect? Explain. ______________________________________________________________________

3.Two researchers make a test concerning standardized exam performance among senior high school students in one of two local communities. Researcher A tests performance from the population in the northern community, where the standard deviation of test scores is 110 (); Researcher B tests performance from the population in the southern community, where the standard deviation of test scores is 60 (). All other things being equal, which researcher has more power to detect an effect? Explain. ______________________________________________________________________