PSY 305 Assignment 1 solution correct answer key 1. A professor has been teaching statistics for many years. His records show that the overall mean for final exam scores is 85 with a standard deviation of 10. He believes that this year’s class is superb to the previous classes. The mean for the 40 students is 90. What is the null hypothesis? What is the research hypothesis? Is this a one or two tailed hypothesis? Which test should you use? Why? Calculate the appropriate statistical test. What is the critical value for α = .05? What do you conclude? 2. A researcher gives a group of participants (n = 15) a memory technique to use. He finds that they remember on average 20 words (sample standard deviation = 3) while the average number of words remembered in the population is 15. What is the null hypothesis? What is the research hypothesis? Is this a one or two tailed hypothesis? Which test should you use? Why? Calculate the appropriate statistical test. What is the critical value for α = .05? What do you conclude? 3. What is the difference between a z-test and a t-test (i.e., when would you use each one)?
University of Phoenix Material
Week Six Homework Exercise
Answerthe following questions, covering material from Ch. 12 of Methods in Behavioral Research:
1. Define the following terms:
· Descriptive statistics
· Scales of measurement
· Measures of central tendency
· Frequency distributions
· Correlation coefficient
· Effect size
· Multiple regression
2. How are group means, percentages, and correlations used to describe research results?
3. How can graphs be used to describe and summarize data?
4. A researcher is studying reading rates in milliseconds per syllable. What scale of measurement—nominal, ordinal, interval, or ratio—is time in milliseconds? Explain your response.
5. Under what circumstances is the median or mode a better measure of central tendency than the mean? Explain your response.
6. True or false: The standard deviation and the range are sensitive to outliers. Explain your response.
7. True or false: The standard deviation can never be 0. Explain your response.
8. A researcher is investigating the effects of anxiety on creativity. Individuals with varying levels of anxiety are asked to complete a measure of creativity. The results show a classic U-shaped distribution; that is, individuals with moderate levels of anxiety score the highest on tests of creativity. Individuals with very low or very high levels of anxiety score much lower on tests of creativity. What would be a good statistic to use in this case? Explain your response.
9. What are some applications of multiple regression models (equations / techniques)? Provide an example.
10. Explain how and why multiple correlations are used as prediction variables?
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