Question

SEX: Sex (1=Male 2=Female)	FIQ: Full-Scale IQ
1	96
1	88
1	85
1	97
1	124
1	101
1	93
1	94
1	114
1	113
2	96
2	87
2	101
2	103
2	127
2	89
2	87
2	103
2	96
2	126

I. What test/procedure did you perform? (6.66 points)

• a. One sided T-test
• b. Two sided T-test
• c. Regression
• d. Confidence interval

II. Statistical interpretation? (6.66 points)

• a. Since P-value is small we are confident that the slope is not zero.
• b. Since P-value is small we are confident that the averages are different.
• c. Since P-value is too large the test is inconclusive.
• d. None of these.

III. Conclusion? (6.66 points)

• a. Yes, we can confirm the assertion.
• b. No, we cannot confirm the assertion.

In what follows use any of the following tests/procedures: Regression, multiple regression, confidence intervals, one sided T-test or two sided T-test. All the procedures should be done with 5% P-value or 95% confidence interval.Some answers are approximated, choose the most appropriate answer. Open Brains data. SETUP: Are the IQ’s for male and female subjects different? Given your job is to confirm or disprove this assertion.

Answer 1

We have performed the analysis using very basic software MSExcel and choose an Independent sample of a two-tailed t-test to confirm the difference in IQ’s for male and female subjects.

Step 1: Type your data into columns or rows in Excel. For example, if you are testing three groups of drugs (including a control), type your data into three columns.

Step 2: Click the “Data” tab and then click “Data Analysis.” If you don’t see Data Analysis, load the Data Analysis Toolpak.

Step 3: Click “t-Test: Two-Sample Assuming Equal Variances” and then click “OK.”

Step 4: Type an input range into the Input Range box(excluding the column names).

Step 5: Select an output range. For example, click the “New Worksheet” radio button.

Step 6: Choose alpha level(0.05).

Step 7: Click “OK.” The results will appear in the worksheet

t-Test: Two-Sample Assuming Equal Variances Mean Variance Observations Pooled Variance Hypothesized Mean Difference Male Female 100.5 101.5 157.6111111 210.2778 10 10 183.9444444 df 18 t Stat P(T<=t) one-tail t Critical one-tail P(T<=t) two-tail t Critical two-tail -0.16487001 0.435441855 1.734063607 0.87088371 2.10092204

H0= IQ’s for male and female subjects (null hypothesis)

Since the test is two-tailed the p-value =

0.87088371

which is much greater than Alpha=0.05 so it appears to have either strong enough evidence to accept the null hypothesis or since P-value is too large the test is inconclusive. We conclude that IQ’s for male and female subjects are the same.