Mark W. Tengler, M.S. PSYC 4730 INFERENTIAL STATISTICS Extra Credit #2 Directions: Answer the questions with the data that is given and only using your formula worksheets and the tables in the back of the book (t Distribution and F Distribution tables). Please show the complete design and your work. Please set up tables to do your calculations similarly to how we did it in class, and then plug the numbers into the correct formulas. Please work individually. This exercise is worth 10 points extra credit and is due on the final exam day. Ch. 9: Numerous studies have shown that IQ scores have been increasing, generation by generation, for years (Flynn, 1984, 1999). The increase is called the Flynn Effect, and the data indicate that the increase appears to be about 7 points per decade. To demonstrate this phenomenon, a researcher obtains an IQ test that was written in 1980. At the time the test was prepared, it was standardized to produce a population mean of µ = 100. The researcher administers the test to a random sample of n = 16 of today’s high school students and obtains a sample mean IQ of M = 121 with SS = 6000. Is this result sufficient to conclude that today’s sample scored significantly higher than would be expected from a population with µ = 100? Use α = .01. Ch. 10: A biopsychologist studies the role of the brain chemical serotonin in aggression. One sample of rats serves as a control group and receives a placebo. A second sample of rats receives a drug that lowers brain levels of serotonin. Then the researcher tests the animals by recording the number of aggressive responses each of the rats display. For the data below, is there a significant effect of the drug on aggression? What, if any, role does serotonin have in aggression? Use an alpha level of α = .05. (note: is this a one-tail or two-tail test?) Lowers Serotonin 5 8 15 16 6 9 (see next page for more) 1 Control 3 6 5 6 8 4 7 Mark W. Tengler, M.S. PSYC 4730 Ch. 13: A developmental psychologist is examining problem-solving ability for grade school children. Random samples of 5-year old, 6-year old, and 7-year old children are obtained with n = 3 in each sample. Each child is given a standardized problem-solving task, and the psychologist records the number of errors. The data are as follows: 5-year olds 5 4 6 a. 6-year olds 6 4 2 7-year olds 0 1 2 Does the data indicate whether there are any significant differences among the three age groups? Use α = .05. Show the complete design, all your work, and report your results professionally. Ch. 14: Complete the matrix for the following scenario: A researcher conducted a two-factor research study using two levels of diet and four levels of exercise with a sample size of n = 6 for each of the unique treatment conditions (i.e. for each group). The table summarizes the results of the analysis, but it is not complete. Fill in the missing values. (Hint: Start with the df values first, which you can calculate from your formula sheet.) Show your work and all calculations. s2 or MS F ratio ______ ______ F = ______ ______ ______ 48 F = ______ 120 ______ ______ F = ______ ______ ______ ______ 600 ______ Source SS df Between groups 280 ______ Main effect of diet ______ Main effect of exercise Diet x Exercise interaction Within groups Total 2