Question

Below is the data for a personality questionnaire measuring conscientiousness. These data were taken from a random sample of 25 undergraduate psychology majors. In the general population, scores on this questionnaire are normally distributed with a mean (μ) of 60. You hypothesize that this sample is not representative of the general population. Specifically, you hypothesize that psychology students form a distinct sub-population, with DIFFERENT conscientiousness, relative to the general population. That is, it would be equally interesting to find out they have higher or lower conscientiousness. Conduct a one-sample t-test by answering the following questions.

Data: N = 25, xbar (sample mean) = 65.12, S_x = 10.17

  a. State the null and alternative hypotheses.

  b. Are you going to be using a one- or two-tailed test? Explain the reason for your choice.

  c. What are the degrees of freedom for this t-test? Find the corresponding critical t-value for Type I error rate (alpha) of α = 0.05?

d. Calculate your observed t-statistic.

e. Compare your observed t-statistic to the critical t-value(s). What do you conclude regarding the null hypothesis?

f. Calculate and interpret follow-up 95% Confidence interval

g. Calculate and interpret the standardized effect size (Cohen's d).

h. What do you conclude about your research question (use your own words, in everyday language)

Answer 1