Question description
Distinguish between descriptive and inferential statistics. Use
examples to illustrate the points you make. (Reference using APA)
2. Specify independent variable, dependent variable, the sample, population, data, and the statistic.
a. A physiologist wants to know whether a particular region of the brain (hypothalamus) is involved in the regulation of eating. An experiment is performed in which 30 rats are selected from the university vivarium and divided into 2 groups. One of the groups receives lesions produced in a neutral area. After recovery from the operations, all animals are given free access to food for 2 weeks., and a record is kept of the daily food intake of each animal. At the end of the 2 week period the mean daily food intake for each group is determined. Finally, these means are compared to see whether the lesions in the hypothalamus have affected the amount eaten.
b. A clinical psychologist is interested in evaluating 3 methods of treating depression: medication, cognitive restructuring, and exercise. A fourth treatment condition, a waiting-only treatment group, is included to provide a baseline control group. Sixty depressed students are recruited from the undergraduate student body at a large state university, and fifteen are assigned to each treatment method. Treatments are administered for 6 months, after which each student is given a questionnaire designed to measure the degree of depression. The questionnaire is scaled from 0 to 100, with higher scores indicating a higher degree of depression. The mean depression values are then computed for the 4 treatments and compared to determine the relative effectiveness of each treatment.
c. A sport psychologist uses visualization in promoting enhanced performance in college athletes. She is interested in evaluating the relative effectiveness of visualization alone versus visualization plus appropriate self-talk. An experiment is conducted with a college basketball team. Ten members of the team are selected. Five are assigned to a visualization alone group, and five are assigned to a visualization plus self-talk group. Both techniques are designed to increase foul shooting accuracy. Each group practices its technique for 1 month. The foul shooting accuracy of each player is measured before and 1 month after beginning practice of the technique. Difference scores are computed for each player, and the means of the difference scores for each group are compared to determine the relative effectiveness of the 2 techniques.
d. A typing teacher believes that a different arrangement of the typing keys will promote faster typing. Twenty secretarial trainees, selected from a large business school, participate in an experiment designed to test this belief. Ten of the trainees learn to type on the conventional keyboard. The other ten are trained using the new arrangement of keys. At the end of the training period, the typing speed in words per minute of each trainee is measured. The mean typing speeds are then calculated for both groups and compared to determine whether the new arrangement has had an effect.
3. Indicate which of the following represent a variable and which a constant:
a. The number of letters in the alphabet
b. Number of hours in a day
c. time at which you eat dinner
d. number of students who major in psychology at your university each year
e. number of centimeters in a meter
f. the amount of sleep you get each night
g. the amount you weigh
h. the volume of a liter
4. Identify which of the following represent continuous variables and which are discrete variables:
a. Time of day
c. Number of bar presses by a rat in a Skinner box
e. Number of words remembered
f. Weight of food eaten
3. Identify the scaling of each of the following variables:
a. Anxiety over public speaking, scored on a scale of 0-100 (Assume the difference in anxiety between adjacent units throughout the scale is not the same).
b. The time it takes to react to the sound of a tone.
c. Ratings of professors by students on a 50-point scale (there is an insufficient basis for assuming equal intervals between adjacent units).