In: Statistics and Probability
TWO MEANS – INDEPENDENT SAMPLES
Choose a variable from the advising.sav data set to compare group means. While the choice of which variable to test is up to you, you must remember that it must be a metric variable. The grouping variable, which is used to define the two groups to be compared, must be categorical. You can look in the “Measure” column of the “Variable View” in the data file for help in determining which is which. The managerial question is whether or not there is a significant difference between the groups for the metric variable you have chosen.
Once you have the results, report your findings using the five step hypothesis testing procedure outlined in class. (See below.) For Step 4, simply cut and paste the SPSS output into the report. This can be done by clicking on the desired portion of the output which will then be highlighted, and then right clicking on the highlighted portion and copying it to your flash drive. (Note that you may want to drop the results into a word document immediately since if you do not have SPSS on your personal laptop, you will not be able to open any SPSS output.) Then state the answer to the managerial question that was initially posed. For example, is there a significant difference between the two groups defined by the grouping variable (which you must identify in your report) for the metric variable tested? Also, interpret the confidence interval provided for the test. Does it indicate a significant difference or not?
PAIRED SAMPLE T-TEST
Choose a pair of metric variables and run a paired sample t-test on the pair. Again, these must be metric variables. The managerial question will be “Is there a significant difference between the two variables?” for the pair. Report your findings using the same procedure described above, including an interpretation of the confidence interval.
REPORT(SAMPLE)
Your report will consist of two hypotheses tests, (one for the independent sample test and one for the paired sample test). It will look something like this (for the independent sample test):
1: H0: μ1= μ2
Ha: μ1 ≠ μ2
2: Two group independent sample t-test (note that SPSS does everything as a t-test regardless of sample size).
3: α=.05 → tcrit = ±whatever the appropriate value is
4
Group Statistics |
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status |
N |
Mean |
Std. Deviation |
Std. Error Mean |
|
dotest |
0 |
185 |
1494.071 |
2249.4948 |
165.3861 |
1 |
50 |
803.280 |
1080.0304 |
152.7394 |
Independent Samples Test |
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Levene's Test for Equality of Variances |
t-test for Equality of Means |
|||||||||
F |
Sig. |
t |
df |
Sig. (2-tailed) |
Mean Difference |
Std. Error Difference |
95% Confidence Interval of the Difference |
|||
Lower |
Upper |
|||||||||
dotest |
Equal variances assumed |
13.465 |
.000 |
2.104 |
233 |
.036 |
690.7914 |
328.2585 |
44.0572 |
1337.5255 |
Equal variances not assumed |
3.068 |
169.287 |
.003 |
690.7914 |
225.1264 |
246.3747 |
1135.2080 |
5: Make a decision regarding the null hypothesis and interpret the confidence interval.
6: Answer the managerial question.
TWO RESULTS AFTER RUNNING
INDEPENDENT
Group Statistics |
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Gender |
N |
Mean |
Std. Deviation |
Std. Error Mean |
|
OverallSatisfaction |
Female |
131 |
4.97 |
1.771 |
.155 |
Male |
145 |
4.99 |
1.488 |
.124 |
Independent Samples Test |
||||||||||
Levene's Test for Equality of Variances |
t-test for Equality of Means |
|||||||||
F |
Sig. |
t |
df |
Sig. (2-tailed) |
Mean Difference |
Std. Error Difference |
95% Confidence Interval of the Difference |
|||
Lower |
Upper |
|||||||||
OverallSatisfaction |
Equal variances assumed |
5.905 |
.016 |
-.120 |
274 |
.904 |
-.024 |
.196 |
-.410 |
.363 |
Equal variances not assumed |
-.119 |
255.054 |
.905 |
-.024 |
.198 |
-.414 |
.366 |
PAIRED
Paired Samples Statistics |
|||||
Mean |
N |
Std. Deviation |
Std. Error Mean |
||
Pair 1 |
DesiredConvenience |
6.20 |
273 |
1.175 |
.071 |
ActualConvenience |
4.55 |
273 |
1.636 |
.099 |
Paired Samples Correlations |
||||
N |
Correlation |
Sig. |
||
Pair 1 |
DesiredConvenience & ActualConvenience |
273 |
.213 |
.000 |
Paired Samples Test |
|||||||||
Paired Differences |
t |
df |
Sig. (2-tailed) |
||||||
Mean |
Std. Deviation |
Std. Error Mean |
95% Confidence Interval of the Difference |
||||||
Lower |
Upper |
||||||||
Pair 1 |
DesiredConvenience - ActualConvenience |
1.648 |
1.799 |
.109 |
1.434 |
1.863 |
15.140 |
272 |
.000 |
PLEASE ANSWER TWO REPORTS INDEPENDENTLY ONE IS INDEPENDENT AND THE OTHER IS PAIRED
AND PLEASE ANSWER AS SAMPLE REPORT STRUCTURE WITH 6 STEPS