Question: ID Salary Compa Midpoint Age 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
ID Salary Compa Midpoint Age 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 60 26.8 34.7 57.9 48.5 74.3 42 23.6 74.2 22.6 23.4 61.7 41.3 22.9 24.9 46.6 66.5 36.3 24.5 34.3 76.7 57.3 22.5 54.7 24.5 23 39.4 75.4 72 46 24 26.9 59.8 26.5 22.6 23.4 23.3 65.4 36.1 24.2 45.2 22.7 77.2 63.2 51 63.7 62.9 69.6 63.5 61.4 1.053 57 31 31 57 48 67 40 23 67 23 23 57 40 23 23 40 57 31 23 31 67 48 23 48 23 23 40 67 67 48 23 31 57 31 23 23 23 57 31 23 40 23 67 57 48 57 57 57 57 57 34 52 30 42 36 36 32 32 49 30 41 52 30 32 32 44 27 31 32 44 43 48 36 30 41 22 35 44 52 45 29 25 35 26 23 27 22 45 27 24 25 32 42 45 36 39 37 34 41 38 0.866 1.120 1.016 1.010 1.109 1.050 1.025 1.107 0.984 1.018 1.082 1.033 0.997 1.084 1.166 1.166 1.170 1.064 1.107 1.145 1.193 0.979 1.140 1.067 0.998 0.985 1.125 1.075 0.958 1.045 0.867 1.049 0.856 0.982 1.017 1.014 1.147 1.164 1.053 1.130 0.989 1.152 1.108 1.062 1.117 1.104 1.221 1.114 1.078 Performance Service Gender Rating 85 80 75 100 90 70 100 90 100 80 100 95 100 90 80 90 55 80 85 70 95 65 65 75 70 95 80 95 95 90 60 95 90 80 90 75 95 95 90 90 80 100 95 90 95 75 95 90 95 80 8 7 5 16 16 12 8 9 10 7 19 22 2 12 8 4 3 11 1 16 13 6 6 9 4 2 7 9 5 18 4 4 9 2 4 3 2 11 6 2 5 8 20 16 8 20 5 11 21 12 0 0 1 0 0 0 1 1 0 1 1 0 1 1 1 0 1 1 0 1 0 1 1 1 0 1 0 1 0 0 1 0 0 0 1 1 1 0 1 0 0 1 1 0 1 0 0 1 0 0 Raise Degree Gender 1 5.7 3.9 3.6 5.5 5.7 4.5 5.7 5.8 4 4.7 4.8 4.5 4.7 6 4.9 5.7 3 5.6 4.6 4.8 6.3 3.8 3.3 3.8 4 6.2 3.9 4.4 5.4 4.3 3.9 5.6 5.5 4.9 5.3 4.3 6.2 4.5 5.5 6.3 4.3 5.7 5.5 5.2 5.2 3.9 5.5 5.3 6.6 4.6 0 0 1 1 1 1 1 1 1 1 1 0 0 1 1 0 1 0 1 0 1 1 0 0 0 0 1 0 0 0 1 0 1 1 0 0 0 0 0 0 0 1 0 1 1 1 1 1 0 0 M M F M M M F F M F F M F F F M F F M F M F F F M F M F M M F M M M F F F M F M M F F M F M M F M M Gr E B B E D F C A F A A E C A A C E B A B F D A D A A C F F D A B E B A A A E B A C A F E D E E E E E Students: Copy the Student Data file data values into this sheet to assist in doing your weekly assignments. The ongoing question that the weekly assignments will focus on is: Are males and fe Note: to simplfy the analysis, we will assume that jobs within each grade comprise eq The column labels in the table mean: ID - Employee sample number Salary - Salary in thousands Age - Age in years Performance Rating - Appraisal rating (e Service - Years of service (rounded) Gender - 0 = male, 1 = female Midpoint - salary grade midpoint Raise - percent of last raise Grade - job/pay grade Degree (0= BS\\BA 1 = MS) Gender1 (Male or Female) Compa - salary divided by midpoint 2251.1 emales paid the same for equal work (under the Equal Pay Act)? qual work. employee evaluation score) Week 1. Measurement and Description - chapters 1 and 2 1 The goal this week is to gain an understanding of our data set - what kind of data we are looking at, some descriptive measurse, and a look at how the data is distributed (shape). Measurement issues. Data, even numerically coded variables, can be one of 4 levels nominal, ordinal, interval, or ratio. It is important to identify which level a variable is, as this impact the kind of analysis we can do with the data. For example, descriptive statistics such as means can only be done on interval or ratio level data. Please list under each label, the variables in our data set that belong in each group. Nominal Ordinal Interval Ratio Gender1 Midpoint Performance Service Gender Grade Compa Salary Degree Raise ID Age b. For each variable that you did not call ratio, why did you make that decision? Gender1, Gender, Degree, Id: Used for labeling purposes or category Midpoint, Grade: Used to show an order or position, sequence only Performance, Compa: Used to show a distinction between something, cannot be mutliplied or divided 2 The first step in analyzing data sets is to find some summary descriptive statistics for key variables. For salary, compa, age, performance rating, and service; find the mean, standard deviation, and range for 3 groups: overall sample, Females, and Males. You can use either the Data Analysis Descriptive Statistics tool or the Fx =average and =stdev functions. (the range must be found using the difference between the =max and =min functions with Fx) functions. Note: Place data to the right, if you use Descriptive statistics, place that to the right as well. Some of the values are completed for you - please finish the table. Salary Compa Age Perf. Rat. Service Overall Mean 45.02 1.0630 35.7 85.9 9.0 Standard Deviation 19.2083 0.0820 8.2513 11.4147 5.7177 Note - data is a sample from the larger company population Range 54.7 0.365 30 45 21 Female Mean 40.25 1.0730 32.5 84.2 7.9 Standard Deviation 18.5 0.0760 6.9 13.6 4.9 Range 54.7 0.242 26.0 45.0 18.0 Male Mean 51.83 1.0530 38.9 87.6 10.0 Standard Deviation 17.7 0.0870 8.4 8.7 6.4 Range 52.5 0.310 28.0 30.0 21.0 3 What is the probability for a: Probability a. Randomly selected person being a male in grade E? 1.0212 b. Randomly selected male being in grade E? 0.083 Note part b is the same as given a male, what is probabilty of being in grade E? c. Why are the results different? 4 A key issue in comparing data sets is to see if they are distributed/shaped the same. We can do this by looking at some measures of where some selected values are within each data set - that is how many values are above and below a comparable value. For each group (overall, females, and males) find: Overall Female Male A The value that cuts off the top 1/3 salary value in each group 57.7 41.0 62.0 "=large" function i The z score for this value within each group? 0.66 0.164 0.563 Excel's standize function ii The normal curve probability of exceeding this score: 0.255 0.435 0.563 1-normsdist function iii What is the empirical probability of being at or exceeding this salary value? 0.5 0.5 0.5 B The value that cuts off the top 1/3 compa value in each group. 1.096 1.096 1.087 i The z score for this value within each group? 0.436 0.388 0.367 ii The normal curve probability of exceeding this score: 0.331 0.349 0.357 iii What is the empirical probability of being at or exceeding this compa value? 0.5 0.5 0.5 C How do you interpret the relationship between the data sets? What do they mean about our equal pay for equal work question? Males appear to have a higher mean age, performance rating, service and salary than the females in this data set. Salary is relative to age, performance ratin 5. What conclusions can you make about the issue of male and female pay equality? Are all of the results consistent? What is the difference between the sal and compa measures of pay? There is not an equality in pay between males and females. Furthermore, the results are inconsistent. There is little difference in the compa measures betw Conclusions from looking at salary results: Male salaries are greater than their female counterparts. Conclusions from looking at compa results: The compa results between males and females are the same. Do both salary measures show the same results? The salary measures do not show the same results. Can we make any conclusions about equal pay for equal work yet? My conclusion is that female employees are paid less than their male counterparts. ing, and service. ween males and females. Week 2 1 Testing means - T-tests In questions 2, 3, and 4 be sure to include the null and alternate hypotheses you will be testing. In the first 4 questions use alpha = 0.05 in making your decisions on rejecting or not rejecting the null hypothesis. Below are 2 one-sample t-tests comparing male and female average salaries to the overall sample mean. (Note: a one-sample t-test in Excel can be performed by selecting the 2-sample unequal variance t-test and making the second variable = Ho value - a Note: These values are not the same as the data the assignment uses. The purpose is to analyze the results of t-tests rather than directly answer our eq Based on these results, how do you interpret the results and what do these results suggest about the population means for male and female average sal Males Ho: Mean salary = Ha: Mean salary =/= Females Ho: Mean salary = Ha: Mean salary =/= 45.00 45.00 45.00 45.00 Note: While the results both below are actually from Excel's t-Test: Two-Sample Assuming Unequal Variances, having no variance in the Ho variable makes the calculations default to the one-sample t-test outcome - we are tricking Excel into doing a one sample Male Ho Female Ho Mean 52 45 Mean 38 45 Variance 316 0 Variance 334.6667 0 Observations 25 25 Observations 25 25 Hypothesized Mean D 0 Hypothesized Mean D 0 df 24 df 24 t Stat 1.9689038266 t Stat -1.913206 P(T<=t) one-tail 0.0303078503 P(T<=t) one-tail 0.033862 t Critical one-tail 1.7108820799 t Critical one-tail 1.710882 P(T<=t) two-tail 0.0606157006 P(T<=t) two-tail 0.067724 t Critical two-tail 2.0638985616 Conclusion: Do not reject Ho; mean equals 45 t Critical two-tail 2.063899 Conclusion: Do not reject Ho; mean equals 45 Note: the Female results are done for you, please complete the male results. Is this a 1 or 2 tail test? 2 tail test Is this a 1 or 2 tail test? 2 tail test - why? Ho:?? is not equal to 45 - why? Ho: ?? is not equal P-value is: 0.0606157006 P-value is: 0.067724 Is P-value < 0.05 (one tail test) or 0.025 (two tail test)? Is P-value < 0.05 (one tail test) or 0.025 (two tail test)? No Why do we not reject the null hypothesis? P-value No Why do we not reject the null hypothesis? P-value is <0.05 greater than (>) rejection alpha Interpretation of test outcomes: The mean salary of both males and females are different from the mean of the population. 2 Based on our sample data set, perform a 2-sample t-test to see if the population male and female average salaries could be equal to each other. (Since we have not yet covered testing for variance equality, assume the data sets have statistically equal variances.) Ho: Ha: Test to use: Male salary mean = Female salary mean Male salary mean =/= Female salary mean t-Test: Two-Sample Assuming Equal Variances Male Mean 52 Variances Observations Pooled Variances Hypothesized Mean Difference df t Stat P(T<=t) one tail t Critical one tail P(T<=t) two tail t Critical two tail 316 25 325.33333 0 48 2.744219 0.004253 1.6772242 Female 38 334.6667 25 0.00850602 2.01063472 P-value is: 0.008506 Is P-value < 0.05 (one tail test) or 0.025 (two tail test)? Reject or do not reject Ho: one tail test reject Ho If the null hypothesis was rejected, calculate the effect size value: If calculated, what is the meaning of effect size measure: 0.7761823 An indication of the difference between the mean salaries of males and females Interpretation: There is enough evidence presented to validate that the mean salary of males is significantly higher than their fe b. Is the one or two sample t-test the proper/correct apporach to comparing salary equality? Why? The two tail test is the better coice when comparing salary equality. The one tail test is unable to provide significance. 3 Based on our sample data set, can the male and female compas in the population be equal to each other? (Another 2-sample t-test.) Again, please assume equal variances for these groups. Ho: The mean compa of males = the mean compa of females Ha: The mean compa of males is not equal to the mean compa of females Statistical test to use: Two sample t-test with an assumption of equal variances Male Female Mean 1.05624 1.06872 Variance 0.00702061 0.004948 25 25 Observation 0.0059845 Pooled Variance 0 Hypothesized Mean Difference 48 df -0.570369 tStat 0.2855439 P(T<=t)one-tail 1.6772242 t Critical one tail 0.5710878 P(T<=t) two tail t Critical two tail 2.01063472 What is the p-value: 0.571 Is P-value < 0.05 (one tail test) or 0.025 (two tail test)? no Reject or do not reject Ho: Do not reject Ho If the null hypothesis was rejected, calculate the effect size value: Does not apply If calculated, what is the meaning of effect size measure: Does not apply Interpretation: There is not enough evidence to support that the mean compa of males are different than that of the females 4 Since performance is often a factor in pay levels, is the average Performance Rating the same for both genders? NOTE: do NOT assume variances are equal in this situation. Ho: The mean performance rating of the males = the mean performance rating of the females Ha: The mean performance rating of the males is not equal to the mean performance rating of the females Test to ust-Test: Two-Sample Assuming Unequal Variances Male Mean Variance Observation Pooled Variance Hypothesized Mean Difference df t Stat P(T<=t) one tail t Critical one tail P(T<=t) two tail Female 87.6 84.2 184.75 75.25 25 25 130 0 48 1.0542952 0.148513 0.2970259 2.0106347 t Critical two tail What is the p-value: 0.29703 Is P-value < 0.05 (one tail test) or 0.025 (two tail test)? no Do we REJ or Not reject the null? Do not reject If the null hypothesis was rejected, calculate the effect size value: Does not apply If calculated, what is the meaning of effect size measure: Does not apply Interpretation: There is not enough evidence to support that the mean performance rating of males is different than that of their 5 If the salary and compa mean tests in questions 2 and 3 provide different results about male and female salary equality, which would be more appropriate to use in answering the question about salary equity? Why? The salary mean test results show that the difference between males and females is statistically substantial. The compa mean test results show that the difference What are your conclusions about equal pay at this point? Overall, males and females are equally paid. alue - a constant.) r our equal pay question. age salaries? sample test for us. heir female counterparts of their female counterparts ference between males and females is not significant. The compa mean test results are more suitable as its measures disregard the impact of grade. Week 3 Paired T-test and ANOVA For this week's work, again be sure to state the null and alternate hypotheses and use alpha = 0.05 for our decision value in the reject or do not reject decision on the null hypothesis. 1 Many companies consider the grade midpoint to be the "market rate" - the salary needed to hire a new employee. Does the company, on average, pay its existing employees at or above the market rate? Use the data columns at the right to set up the paired data set for the analysis. Salary Midpoint Diff Null Hypothesis: Alt. Hypothesis: Statistical test to use: What is the p-value: Is P-value < 0.05 (one tail test) or 0.025 (two tail test)? What else needs to be checked on a 1-tail test in order to reject the null? Do we REJ or Not reject the null? If the null hypothesis was rejected, what is the effect effect size meaning of size value: measure: Interpretation of test results: Let's look at some other factors that might influence pay - education(degree) and performance ratings. 2 Last week, we found that average performance ratings do not differ between males and females in the population. Now we need to see if they differ among the grades. Is the average performace rating the same for all grades? (Assume variances are equal across the grades for this ANOVA.) Here are the data values sorted by grade level. The rating values sorted by grade have been placed in columns I - N for you. A B C D E 90 80 100 90 85 Null Hypothesis: Ho: means equal for all grades 80 75 100 65 100 Alt. Hypothesis: Ha: at least one mean is unequal 100 80 90 75 95 Place B17 in Outcome range box. 90 70 80 90 55 80 95 80 95 90 85 80 95 65 90 90 70 75 95 95 60 90 90 95 75 80 95 90 100 Interpretation of test results: What is the p-value: Is P-value < 0.05? Do we REJ or Not reject the null? 0.57 If the ANVOA was done correctly, this is the p-value shown. F 70 100 95 95 95 95 If the null hypothesis was rejected, what is the effect size value (eta squared): Meaning of effect size measure: What does that decision mean in terms of our equal pay question: 3 While it appears that average salaries per each grade differ, we need to test this assumption. Is the average salary the same for each of the grade levels? Use the input table to the right to list salaries under each grade level. (Assume equal variance, and use the analysis toolpak function ANOVA.) Null Hypothesis: If desired, place salaries per grade in these columns A B C D E Alt. Hypothesis: F Place B51 in Outcome range box. Note: Sometimes we see a p-value in the format of 3.4E-5; this means move the decimal point left 5 places. In this example, the p-value is 0.000034 What is the p-value: Is P-value < 0.05? Do we REJ or Not reject the null? If the null hypothesis was rejected, calculate the effect size value (eta squared): If calculated, what is the meaning of effect size measure: Interpretation: 4 The table and analysis below demonstrate a 2-way ANOVA with replication. Please interpret the results. Note: These values are not the same as the data the assignment uses. The purpose of this question is to analyze the result of a 2-way ANOVA test rather than directly ans BA MA Ho: Average compas by gender are equal Male 1.017 1.157 Ha: Average compas by gender are not equal 0.870 0.979 Ho: Average compas are equal for each degree 1.052 1.134 Ha: Average compas are not equal for each degree 1.175 1.149 Ho: Interaction is not significant 1.043 1.043 Ha: Interaction is significant 1.074 1.134 1.020 1.000 Perform analysis: 0.903 1.122 0.982 0.903 Anova: Two-Factor With Replication 1.086 1.052 1.075 1.140 SUMMARY BA MA Total 1.052 1.087 Male 1.096 1.050 Female Count 12 12 24 1.025 1.161 Sum 12.349 12.9 25.249 1.000 1.096 Average 1.029083333 1.075 1.0520417 0.956 1.000 Variance 0.006686447 0.006519818 0.006866 1.000 1.041 1.043 1.043 Female 1.043 1.119 Count 12 12 24 1.210 1.043 Sum 12.791 12.787 25.578 1.187 1.000 Average 1.065916667 1.065583333 1.06575 1.043 0.956 Variance 0.006102447 0.004212811 0.0049334 1.043 1.129 1.145 1.149 Total Count Sum Average 24 24 25.14 25.687 1.0475 1.070291667 Variance 0.006470348 0.005156129 ANOVA Source of Variation SS Sample 0.002255021 Columns 0.006233521 (This is the row variable or gend 1 0.0062335 1.060054 0.3088296 4.0617065 (This is the column variable or D Interaction 0.006417188 1 0.0064172 1.0912878 0.3018915 4.0617065 Within Total 0.25873675 0.273642479 df MS F P-value F crit 1 0.002255 0.3834821 0.538939 4.0617065 44 0.0058804 47 Interpretation: For Ho: Average compas by gender are equal Ha: Average compas by gender are not equal What is the p-value: Is P-value < 0.05? Do you reject or not reject the null hypothesis: If the null hypothesis was rejected, what is the effect size value (eta squared): Meaning of effect size measure: For Ho: Average compas are equal for all degrees Ha: Average compas are not equal for all grades What is the p-value: Is P-value < 0.05? Do you reject or not reject the null hypothesis: If the null hypothesis was rejected, what is the effect size value (eta squared): Meaning of effect size measure: For: Ho: Interaction is not significant Ha: Interaction is significant What is the p-value: Is P-value < 0.05? Do you reject or not reject the null hypothesis: If the null hypothesis was rejected, what is the effect size value (eta squared): Meaning of effect size measure: What do these three decisions mean in terms of our equal pay question: Place data values in these columns 5. Using the results up thru this week, what are your conclusions about gender equal pay for equal work at this point? Dif swer our equal pay question. der.) Degree.) ns 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. Mean St error t value Low to High Males Females
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