| Week 4 | Confidence Intervals and Chi Square (Chs 11 - 12) |
| For questions 3 and 4 below, be sure to list the null and alternate hypothesis statements. Use .05 for your significance level in making your decisions. |
| For full credit, you need to also show the statistical outcomes - either the Excel test result or the calculations you performed. |
| 1 | Using our sample data, construct a 95% confidence interval for the population's mean salary for each gender. |
| | Interpret the results. How do they compare with the findings in the week 2 one sample t-test outcomes (Question 1)? |
| | | Mean | St error | t value | | Low | to | High |
| | Males |
| | Females |
| | <Reminder: standard error is the sample standard deviation divided by the square root of the sample size.> |
| Interpretation: |
| 2 | Using our sample data, construct a 95% confidence interval for the mean salary difference between the genders in the population. |
| | How does this compare to the findings in week 2, question 2? |
| | Difference | St Err. | T value | | | Low | to | High |
| | | | | Yes/No |
| | Can the means be equal? | | | | Why? |
| | How does this compare to the week 2, question 2 result (2 sampe t-test)? |
| a. | Why is using a two sample tool (t-test, confidence interval) a better choice than using 2 one-sample techniques when comparing two samples? |
| 3 | We found last week that the degrees compa values within the population. |
| | do not impact compa rates. This does not mean that degrees are distributed evenly across the grades and genders. |
| | Do males and females have athe same distribution of degrees by grade? |
| | (Note: while technically the sample size might not be large enough to perform this test, ignore this limitation for this exercise.) |
| | What are the hypothesis statements: |
| | Ho: |
| | Ha: |
| Note: You can either use the Excel Chi-related functions or do the calculations manually. |
| | Data input tables - graduate degrees by gender and grade level |
| OBSERVED | A | B | C | D | E | F | Total | | Do manual calculations per cell here (if desired) |
| M Grad | | | | | | | | | A | B | C | D | E | F |
| Fem Grad | | | | | | | | M Grad |
| Male Und | | | | | | | | Fem Grad |
| Female Und | | | | | | | | Male Und |
| | | | | | | | | Female Und |
| | | | | | | | | | Sum = |
| EXPECTED |
| M Grad | | | | | | | | For this exercise - ignore the requirement for a correction |
| Fem Grad | | | | | | | | for expected values less than 5. |
| Male Und |
| Female Und |
| Interpretation: |
| | | | | What is the value of the chi square statistic: |
| | | | | What is the p-value associated with this value: |
| | | | | Is the p-value <0.05? |
| | | | | Do you reject or not reject the null hypothesis: |
| | | | | If you rejected the null, what is the Cramer's V correlation: |
| | | | | What does this correlation mean? |
| | | | | What does this decision mean for our equal pay question: |
| 4 | Based on our sample data, can we conclude that males and females are distributed across grades in a similar pattern |
| | within the population? |
| | What are the hypothesis statements: |
| | Ho: |
| | Ha: |
| | | | | | | | | | | Do manual calculations per cell here (if desired) |
| | | A | B | C | D | E | F | | | A | B | C | D | E | F |
| | OBS COUNT - m | | | | | | | | M |
| | OBS COUNT - f | | | | | | | | F |
| | | | | | | | | | Sum = |
| | EXPECTED |
| | | | | What is the value of the chi square statistic: |
| | | | | What is the p-value associated with this value: |
| | | | | Is the p-value <0.05? |
| | | | | Do you reject or not reject the null hypothesis: |
| | | | | If you rejected the null, what is the Phi correlation: |
| | | | | What does this correlation mean? |
| | | | | What does this decision mean for our equal pay question: |
| 5. How do you interpret these results in light of our question about equal pay for equal work? |