A research article included the following table: Mean Score on Four Questionnaire Scales Before and After the Experimental Manipulation Which of the following differences was NOT statistically significant?

For each of the following studies, indicate whether you would use a t test for a single sample, t test for dependent means, or a t test for independent means. (a) A school counselor randomly assigns a group of 50 high school students to receive a new assertiveness training program and 45 other high school students to receive the standard after-school program that focuses on social skills. The counselor later measures how well each group performs on a measure of interpersonal assertiveness. (b) A psychologist measures 100 patients in terms of their anxiety levels before and after undergoing a newly developed treatment. (c) The coach of a college football team conducts an informal survey showing that members of the team study an average of 3.5 hours per day. The coach makes the claim that this is equivalent to the amount of time students at the college study in general. An instructor believes that the coach is incorrect and randomly selects 50 students from the college and asks them how much they study each day. These 50 students report studying an average of 5.2 hours per day. (d) A school psychologist tests the memory scores of each of a group of 15 students twice, once while in a very noisy room and once while in a quiet room and then compares the scores. (e) A student counselor measures the intelligence of college students (n = 25) who are first born in their families compared to those who were born last in their families (n = 40).

Chapter 9

A school counselor wants to test a technique to reduce procrastination in students. Students time their procrastination for a week, which is used as a pretest indicator of procrastination. Students then attend a workshop in which they are instructed to use a specific warm-up exercise for studying by focusing on a pleasant activity. For the next week, students again time their procrastination. The counselor then uses the time from this week as the posttest (after) measure. Suppose the counselor found the sum of squared deviations from the mean of the sample to be 135 after testing 10 people. What would be the estimated population variance?

A sample has individuals with scores of 1, 3, 5, 6, and 6. What is the estimated population variance?

An organizational psychologist conducts a t test for dependent means in which it is predicted that there will be a decrease in unemployment from before to after a job-skills training program. The cutoff t needed is -1.833. The standard deviation of the distribution of means of change scores is 2.0, and the mean change score for the sample studied is an increase of 5.2. What is the appropriate conclusion?

A school counselor wants to test a technique to reduce procrastination in students. Students time their procrastination for a week, which is used as a pretest indicator of procrastination. Students then attend a workshop in which they are instructed to use a specific warm-up exercise for studying by focusing on a pleasant activity. For the next week, students again time their procrastination. The counselor then uses the time from this week as the posttest (after) measure. Assume the counselor wants to examine whether there is a change (either an increase or decrease) in procrastination after attending his workshop. If the counselor tests 10 students using the .05 level of significance, what would be the cutoff t score(s)? (A t table should not be necessary.)

Ratio and Proportion 26)  500 people for 3000 tickets.  How many tickets will one person receive?

If three samples have means of 10, 20, and 15, respectively, what is their grand mean?

Ratio and Proportion 30)  57 books to 95 students, how many books to 5 students?