Practical exercises - Answers
<< back to practical exercises
To answer this question, we employ the goodness-of-fit chi square test.
First of all, enter the data in the computer. Use 1 for those choosing
psychology as a major, 2 for those choosing history and 3 for those choosing
sociology; enter 15 times the digit 1, 11 times the digit 2, and 12 times the
digit 3, all in one column. Having set the data in the computer, you follow the
steps presented in the text (p. 384). The result obtained is shown below.
Test Statistics
|
|
Subject choice |
|
Chi-Square(a) |
.684 |
|
df |
2 |
|
Asymp. Sig. |
.710 |
The important figure to consider here is .710, which
indicates that the differences in the choice of study directions among the
students considered in the study are not significant. Remember, significance is
accepted if the level is .01 or smaller.
To answer these questions we employ a chi square test. First of all, the
tabular data must be entered in the computer. We demonstrated earlier how this
is accomplished. The variables are 'couples' (1 for same-sex and 2 for
other-sex couples) and 'comitmnt' (1 for high commitment and 2 for low
commitment). The extra variable 'count' is set to accommodate the figures.
Having set the data as required, we proceed as follows:
Go to Analyse/Descriptive
Statistics/Crosstabs.
Transfer 'couples' to the top row and 'comitmnt' to the
bottom row.
Go to Data in the
menus and click Weight cases.
In the new dialog box activate Weight cases by clicking on the button in front of it.
Transfer 'count' to the Frequency
Variable box, by clicking on the triangle in front of it.
Click OK, and in the new dialog box click Statistics and activate Chi square.
Click Continue
and then OK to initiate processing.
Following this, you obtain the following table:
Chi-Square
Tests
|
|
Value |
df |
Asymp. Sig. (2-sided) |
Exact Sig. (2-sided) |
Exact Sig. (1-sided) |
|
Pearson Chi-Square |
1.220b |
1 |
.269 |
|
|
|
Continuity Correctiona |
.934 |
1 |
.334 |
|
|
|
Likelihood Ratio |
1.221 |
1 |
.269 |
|
|
|
Fisher's Exact Test |
|
|
|
.334 |
.167 |
|
Linear-by-Linear Association |
1.215 |
1 |
.270 |
|
|
|
N of Valid Cases |
214 |
|
|
|
|
a
Computed only for a 2x2 table
b
0 cells (.0%) have expected count less than 5. The minimum expected
count is 46.00.
Examining the significance level (.269) we can conclude that there is no
evidence to suggest that the degree of commitment of the two groups of couples
varies significantly.
We employ exactly the same procedure followed in Exercise 14, with the
exception that we activate Phi and Cramer's V. The results produced, using this procedure, are shown
below.
Symmetric
Measures
|
|
Value |
Approx. Sig. |
|
|
Nominal by Nominal |
Phi |
.076 |
.269 |
|
|
Cramer's V |
.076 |
.269 |
|
N of Valid Cases |
214 |
|
|
a
Not assuming the null hypothesis.
b
Using the asymptotic standard error assuming the null hypothesis.
As in the previous question, the important figure here is 'Approx.
Sig.', the significance level, which is not only the same for both measures but
also the same as that produced by the chi square test reported in the previous
question.
To answer the research question we employ the one-sample t-test. Here we
set the scores in one column. We name the variable 'Satisfac' (for
satisfaction). Remember that we are comparing means here. Further, we proceed
as follows:
Select Analyze/Compare means/One-sample test.
Transfer
'satisfac' to the Test variable(s)
box.
Type 6.2 in
the Test value box.
Click Options and set Confidence interval to 95 per cent.
Activate Exclude cases analysis by analysis (in
Missing values sector).
Click Continue and then OK.
Following this we obtain the following figures:
One-Sample
Test
|
|
Test Value = 6.2 |
|||||
|
|
t |
df |
Sig. (2-tailed) |
Mean Difference |
95% Confidence Interval of the Difference |
|
|
|
|
|
|
|
Lower |
Upper |
|
Women's satisfaction |
.764 |
24 |
.452 |
.152 |
-.26 |
.56 |
Of all data, the indicator of the significance level (.452) is the one
we need to concentrate on. Given that this is greatly above the acceptable
level of .05, we can conclude that the difference between the recorded scores
and the average marital satisfaction is not significant.
Given the nature of data and the level of measurement, as well as the
relationship between the samples (they are paired), the most appropriate test
to employ is the t-test for paired samples. After data entry, and using the
variable names Flyflex and placebo, we proceed with the computation following
the steps introduced in the text. The answer to the question is shown in the
following table.
Paired Samples Test
|
|
Paired Differences |
t |
df |
Sig. (2-tailed) |
|||||
|
|
Mean |
Std. Dev. |
Std. Error Mean |
95% Confidence Interval of the
Difference |
|
|
|
||
|
|
|
|
|
Lower |
Upper |
|
|
|
|
|
Pair 1 |
Using Flyflex
Using placebo |
-1.00 |
.289 |
.058 |
-1.12 |
-.881 |
-17.32 |
24 |
.000 |
The level of significance is .000, which is the highest level of
significance one can get. This indicates that the differences in the test
performance of the two groups of respondents are significant. In more general
terms, it means that taking Flyflex produces significantly different (and here,
lower) anxiety scores than taking a placebo.
Given the nature of the data and the number of samples, One-way ANOVA is
the most appropriate test that could address the issues included in the question
most satisfactorily. The variables are 'Achievemt' (dependent variable) and
'Residenc' (independent variable or factor). The residence is numbered 1 (city
students), 2 (town students) and 3 (remote students). Set each student's score
in one column, followed by the student's residence in the second column. The
steps to take from here are those given in the text, namely
Select Analyze/Compare means/One Way ANOVA.
Transfer
'achievemt' to the Dependence List
box.
Transfer
'residenc' to the Factor box.
Click Options and then Descriptive, then Continue
and OK.
ANOVA
Achievement score
|
|
Sum of Squares |
df |
Mean Square |
F |
Sig. |
|
Between Groups |
39.433 |
2 |
19.717 |
10.450 |
.000 |
|
Within Groups |
107.550 |
57 |
1.887 |
|
|
|
Total |
146.983 |
59 |
|
|
|
As in the previous exercise, so here, the level of significance is .000.
This indicates that the differences in the test performance of the three groups
of respondents are significant. This means that scholastic achievement is
significantly affected by the students' place of residence.