–EDUC 606–

Learning Activity 3 Student Instructions

This learning activity consists of a variety of problems from Chapters 13–15. Spaces for answers are provided; please type your answers directly in the document. Consider highlighting, starring*, or changing the font color of answers for ease of instructor grading.

1. (20 Pts, 1 Pt each). Calculate the mean, median, mode, standard deviation, and range for the following sets of measurements (fill out the table):

a. 14, 8, 7, 7, 9

b. 20, 13, 12, 11, 9

c. 58, 58, 58, 58, 58

d. 13, 13, 10, 9, 7, 62

DISTRIB	MEAN	MEDIAN	MODE	SD	RANGE
a.
b.
c.
d.

2. (20 Pts, 5 pts each) Answer the following questions.

a. Why is the SD in (d) so large compared to the SD in (b)?

b. Why is the mean so much higher in (d) than in (b)?

c. Why is the median relatively unaffected?

d. Which measure of central tendency best represents the set of scores in (d)? Why?

3. (4 pts) Determine the semi-interquartile range for the following set of scores.

90, 120, 95, 95, 110, 105, 115, 115, 100, 105, 100, 105

4. (24 pts, 2 pts each) Fill in the blanks on the table with the appropriate raw scores, z-scores, T-scores, and approximatepercentile ranks. You may refer to the distribution curve below.

Note: the Mean = 50, SD = 5.

RAW	z	T	Percentile
30
	3
		65
			1.07

5. (4 pts, 2 pts each) The following are the means and standard deviations of some well-known standardized tests, referred to as Test A, Test B, and Test C. All three yield normal distributions.

Test	Mean	Standard Deviation
Test A	500	100
Test B	150	8
Test C	70	15

a. (2 pts) A score of 450 on Test A corresponds to what score on Test B?

b. (2 pts) A score of 625 on Test A corresponds to what score on Test C?

6. (12 pts, 2 pts each) The Graduate Record Exam (GRE) has a combined verbal and quantitative mean of 1000 and a standard deviation of 200. Scores range from 200 to 1600 and are approximately normally distributed. For each of the following problems:

(a) Indicate the percentage or score called for by the problem.

(b) Select the appropriate distribution curve (from below) that relates to the problem.

a. (2 pts) What percentage of the persons who take the test score above 1400? ___

(2 pts) Type the curve best representing your answer: ___

b. (2 pts) What percentage of the persons who take the test score above 700? ___

(2 pts) Type the curve best representing your answer: ___

c. (2 pts) Below what score do the bottom 30.9% of the test-takers score? ___

(2 pts) Type the curve best representing your answer: ___

7. (16 pts, varied) Refer to the following data and scatterplots to respond to questions 7a-f.

Figure B

Figure A

Individual	Age	Score on Earning Potential
1	24	5
2	56	19
3	78	8
4	76	8
5	80	7
6	35	14
7	32	12
8	42	18
9	18	2
10	17	1
11	35	20
12	36	16
13	29	10
14	60	19
15	65	13
16	78	11

Figure C

Figure A represents a scatterplot constructed from the data; Figure B represents a regression line drawn through the scatterplot that “fits” the data points reasonably well; Figure C represents an ellipse drawn around the data points.

a.(2 pts.) What is the overall direction of the correlation? ___

b.(2 pts.) Estimate the strength of the correlation coefficient:___

Consider Figure D (below).

Figure D

c.(2 pts.) Using only the data points associated with age of 60 and above; what effect does this have on the directionandstrength of the correlation coefficient?

d.(4 pts.) Explain why this is the case.

e.(2 pts.) Why is it beneficial to examine truncated parts of this graph instead of the graph as a whole?

f.(4 pts.) Identify how likely it is that a causal relationship has been indicated.