Statistical Methods for Psychology

Exercises 57

2.9 In Exercise 2.8, what would be the first and third quartiles for males and females?

2.10 The following stem-and-leaf displays show the individual grades referred to in Exercise 2.8
separately for males and females. From these results, what would you conclude about any
differences between males and females?

2.11 What would you predict to be the shape of the distribution of the number of movies attended
per month for the next 200 people you meet?

2.12 Draw a histogram for the data for GPA in Appendix: Data Set referred to at the beginning of
these exercises. (These data can also be obtained at http://www.uvm.edu/~dhowell/methods7/
DataFiles/Add.dat.)

2.13 Create a stem-and-leaf display for the ADDSC score in Appendix: Data Set

2.14 In a hypothetical experiment, researchers rated 10 Europeans and 10 North Americans on a
12-point scale of musicality. The data for the Europeans were [10 8 9 5 10 11 7 8 2 7].
Using Xfor this variable,
a. what are , , and?
b. calculate
c. write the summation notation from part (b) in its most complex form.

2.15 The data for the North Americans in Exercise 2.17 were [9 9 5 3 8 4 6 6 5 2]. Using Yfor
this variable,
a. what are and
b. calculate

2.16 Using the data from Exercise 2.14,

a. calculate and.

b. calculate where N 5 the number of scores.

c. what do you call what you calculated in part (b)?

2.17 Using the data from Exercise 2.15,

a. calculate and.

b. calculate

gY^22

(©Y)^2

N

N 21

(gY)^2 gY^2

gX>N,

(gX)^2 gX^2

gY.

Y 1 Y 10?

gX.

X 3 X 5 X 8

Stem-and-leaf of Percent Stem-and-leaf of Percent

Sex 5 1 (Male) N 529 Sex 5 2 (Female) N 578

Leaf Unit 5 0.010 Leaf Unit 5 0.010

3 6 677 2 6 77

36 368

3 7 6 7 000

5 7 33 10 7 2233

7 7 45 15 7 45555

77 157

10 7 999 22 7 8899999

12 8 01 34 8 011111111111

14 8 22 (8) 8 22222233

(4) 8 4455 36 8 445555555

11 8 6677 27 8 666777777

7 8 8 18 8 888889999

6 9 9 9 00001

6 9 23 4 9 333

4 9 4445 1 9 5