Time to Practice – Week Three PSYCH/625 Version 1


Time to Practice – Week Three

Complete both Part A and Part B below.

Part A

  1.  For the following research questions, create one null hypothesis, one directional research hypothesis, and one non-directional research hypothesis
    1. What are the effects of attention on out-of-seat classroom behavior?
    2. What is the relationship between the quality of a marriage and the quality of the spouses’ relationships with their siblings?
  1.  Provide one research hypothesis and an equation for each of the following topics:
    1. The sum of money paid on food among undergraduate students and undergraduate student-athletes.
    2. The effects of Drug A and Drug B on a disease.
    3. The time to finish a task in Method one and Method two.
  2. Why does the null hypothesis presume no relationship between variables?
  3. Create a research hypothesis tested using a one-tailed test and a research hypothesis tested using a two-tailed test
  4.  What does the critical value represent?
  5. Given the following information, would your decision be to reject or fail to reject the null hypothesis?

Setting the level of significance at .05 for decision making, provide an explanation for your conclusion.

  1. Why is it harder to find a significant outcome (all other things being equal) when the research hypothesis is being tested at the .01 rather than the .05 level of significance?
  2. Why should we think in terms of “failing to reject” the null rather than just accepting it?
  3. When is it appropriate to use the one-sample z test?

Part B

Complete the following questions. Be specific and provide examples when relevant.

Cite any sources consistent with APA guidelines.


  • The average raw math achievement score for third graders at a Smith elementary school is 137; There are 100 third graders at Smith Elementary school. Third graders statewide score an average of 124 with a standard deviation of 7. Are the Smith third graders better at math than third graders throughout the state? Perform the correct statistical test, applying the eight steps of the hypothesis testing process as demonstrated on pp. 185–187 of Statistics for People Who (Think they) Hate Statistics.
  • What is a research question that you would like to answer? Write the null and research hypotheses. Would you use a one- or two-tailed test? Why?
  • What do we mean when we say that a statistical result is significant? What is the difference between a statistically significant and a meaningful result? Why is statistical significance important?
  • Describe a Type I error for the previous study that compares third graders’ math achievement. Describe a Type II error for that study.
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