| Score: | Week 5 | Correlation and Regression |
| <1 point> | 1. | Create a correlation table for the variables in our data set. (Use analysis ToolPak or StatPlus:mac LE function Correlation.) |
| | | a. | Reviewing the data levels from week 1, what variables can be used in a Pearson's Correlation table (which is what Excel produces)? |
| | | b. Place table here (C8): |
| | | c. | Using r = approximately .28 as the signicant r value (at p = 0.05) for a correlation between 50 values, what variables are |
| | | | significantly related to Salary? |
| | | | To compa? |
| | | d. | Looking at the above correlations - both significant or not - are there any surprises -by that I |
| | | | mean any relationships you expected to be meaningful and are not and vice-versa? |
| | | e. | Does this help us answer our equal pay for equal work question? |
| <1 point> | 2 | | Below is a regression analysis for salary being predicted/explained by the other variables in our sample (Midpoint, |
| | | | age, performance rating, service, gender, and degree variables. (Note: since salary and compa are different ways of |
| | | | expressing an employee’s salary, we do not want to have both used in the same regression.) |
| | | | Plase interpret the findings. |
| | | | Ho: The regression equation is not significant. |
| | | | Ha: The regression equation is significant. |
| | | | Ho: The regression coefficient for each variable is not significant | | | | | | Note: technically we have one for each input variable. |
| | | | Ha: The regression coefficient for each variable is significant | | | | | | Listing it this way to save space. |
| | | | Sal |
| | | | SUMMARY OUTPUT |
| | | | Regression Statistics |
| | | | Multiple R | 0.9915590747 |
| | | | R Square | 0.9831893985 |
| | | | Adjusted R Square | 0.9808437332 |
| | | | Standard Error | 2.6575925726 |
| | | | Observations | 50 |
| | | | ANOVA |
| | | | | df | SS | MS | F | Significance F |
| | | | Regression | 6 | 17762.2996738743 | 2960.383278979 | 419.1516111294 | 1.8121523852609E-36 |
| | | | Residual | 43 | 303.7003261257 | 7.062798282 |
| | | | Total | 49 | 18066 |
| | | | | Coefficients | Standard Error | t Stat | P-value | Lower 95% | Upper 95% | Lower 95.0% | Upper 95.0% |
| | | | Intercept | -1.7496212123 | 3.6183676583 | -0.4835388157 | 0.6311664899 | -9.0467550427 | 5.547512618 | -9.0467550427 | 5.547512618 |
| | | | Midpoint | 1.2167010505 | 0.0319023509 | 38.1382881163 | 8.66416336978111E-35 | 1.1523638283 | 1.2810382727 | 1.1523638283 | 1.2810382727 |
| | | | Age | -0.0046280102 | 0.065197212 | -0.0709847876 | 0.9437389875 | -0.1361107191 | 0.1268546987 | -0.1361107191 | 0.1268546987 |
| | | | Performace Rating | -0.0565964405 | 0.0344950678 | -1.6407110971 | 0.1081531819 | -0.1261623747 | 0.0129694936 | -0.1261623747 | 0.0129694936 |
| | | | Service | -0.0425003573 | 0.0843369821 | -0.5039350033 | 0.6168793519 | -0.2125820912 | 0.1275813765 | -0.2125820912 | 0.1275813765 |
| | | | Gender | 2.420337212 | 0.8608443176 | 2.8115852804 | 0.0073966188 | 0.684279192 | 4.156395232 | 0.684279192 | 4.156395232 |
| | | | Degree | 0.2755334143 | 0.7998023048 | 0.3445019009 | 0.732148119 | -1.3374216547 | 1.8884884833 | -1.3374216547 | 1.8884884833 |
| | | | Note: since Gender and Degree are expressed as 0 and 1, they are considered dummy variables and can be used in a multiple regression equation. |
| | | | Interpretation: |
| | | | For the Regression as a whole: |
| | | | | | | What is the value of the F 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: |
| | | | | | | What does this decision mean for our equal pay question: |
| | | | For each of the coefficients: | | | | Intercept | Midpoint | Age | Perf. Rat. | Service | Gender | Degree |
| | | | | | | What is the coefficient's p-value for each of the variables: |
| | | | | | | Is the p-value < 0.05? |
| | | | | | | Do you reject or not reject each null hypothesis: |
| | | | | | | What are the coefficients for the significant variables? |
| | | | | | | Using only the significant variables, what is the equation? | Salary = |
| | | | | | | Is gender a significant factor in salary: |
| | | | | | | If so, who gets paid more with all other things being equal? |
| | | | | | | How do we know? |
| <1 point> | 3 | | Perform a regression analysis using compa as the dependent variable and the same independent |
| | | | variables as used in question 2. Show the result, and interpret your findings by answering the same questions. |
| | | | Note: be sure to include the appropriate hypothesis statements. |
| | | | Regression hypotheses |
| | | | Ho: |
| | | | Ha: |
| | | | Coefficient hyhpotheses (one to stand for all the separate variables) |
| | | | Ho: |
| | | | Ha: |
| | | | Place D94 in output box. |
| | | | Interpretation: |
| | | | For the Regression as a whole: |
| | | | | | | What is the value of the F 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: |
| | | | | | | What does this decision mean for our equal pay question: |
| | | | For each of the coefficients: | | | | Intercept | Midpoint | Age | Perf. Rat. | Service | Gender | Degree |
| | | | | | | What is the coefficient's p-value for each of the variables: |
| | | | | | | Is the p-value < 0.05? |
| | | | | | | Do you reject or not reject each null hypothesis: |
| | | | | | | What are the coefficients for the significant variables? |
| | | | | | | Using only the significant variables, what is the equation? | Compa = |
| | | | | | | Is gender a significant factor in compa: |
| | | | | | | If so, who gets paid more with all other things being equal? |
| | | | | | | How do we know? |
| <1 point> | 4 | | Based on all of your results to date, |
| | | | Do we have an answer to the question of are males and females paid equally for equal work? |
| | | | | | If so, which gender gets paid more? |
| | | | | | How do we know? |
| | | | Which is the best variable to use in analyzing pay practices - salary or compa? Why? |
| | | | What is most interesting or surprising about the results we got doing the analysis during the last 5 weeks? |
| <2 points> | 5 | | Why did the single factor tests and analysis (such as t and single factor ANOVA tests on salary equality) not provide a complete answer to our salary equality question? |
| | | | What outcomes in your life or work might benefit from a multiple regression examination rather than a simpler one variable test? |