(4) Complete the missing numbers. Descriptive Statistics N Range Minimum Maximum Mean Std. Deviation Variance
-
(4)
Complete the missing numbers.
1 ) _____________________Descriptive Statistics N Range Minimum Maximum Mean Std. Deviation Variance Skewness Kurtosis Statistic Statistic Statistic Statistic Statistic Std. Error Statistic Statistic Statistic Std. Error Statistic Std. Error Checkout line wait times were reasonable 144 1 1 10 7.34 2 2.129 3 -.635 .202 -.361 .401 Valid N (listwise) 144
2 ) _____________________
3 ) ___ __________________
4 ) Does the distribution tail to the left or right. Explain________________________ -
(1 4 ) From the Secret Shopper Survey-
Assume that prior studies show scores on employee knowledge = 7.2. Using the compare means process and a one sample t-test examine the results to see if there is a statistically significant difference. The results are displayed below- you do not have to run this file—but y ou need to set this up utilizing the FIVE step process we used in class. You will have to look up a critical value from the t-table and comp are it to the actual value, utilizing the 95% confidence level . Assume we do not have any prior reason to know whether these students will rate our employees ’ knowledge higher or lower.One-Sample Statistics N Mean Std. Deviation Std. Error Mean When asked a question the employee(s) was/were knowledgeable 153 7.80 1.775 .143 One-Sample Test Test Value = 7.2 t df Sig. (2-tailed) Mean Difference 95% Confidence Interval of the Difference Lower Upper When asked a question the employee(s) was/were knowledgeable 4.164 152 .000 .597 .31 .88
1) (10)Set up in the Five STEP Process (make sure you look up the critical t –value)
2) (4) Comment on whether you have Practical significance based on calculating
Cohen’s d . Show calculation and explain what it means in terms of practical sign ificance and its relative strength. -
(
10
)
CROSSTABS-
from Secret Shoppers data
A Crosstabulations & Chi-square comparison on question 10 having to do with "when checking out I received proper service" is displayed below.When checking out I received proper service * GENDER Crosstabulation Count GENDER MALE FEMALE Total When checking out I received proper service VERY POOR SERVICE 2 0 2 MODERATELY POOR SERVICE 1 0 1 QUITE POOR 2 1 3 SERVICE SO SO 1 1 2 OKAY -NOT GREAT 2 5 7 OKAY-SLIGHLY POSITIVE 4 4 8 MODERATELY GOOD 9 6 15 QUITE GOOD 21 10 31 EXCELLENT 13 25 38 SUPERIOR 12 20 32 Total 67 72 139
Set up in the Five STEP Process (make sure you look up the appropriate Chi-square value)C hi-Square Tests Value df Asymp. Sig. (2-sided) Pearson Chi-Square 14.751 a 9 .098 Likelihood Ratio 16.117 9 .064 Linear-by-Linear Association 4.205 1 .040 N of Valid Cases 139 - 12 cells (60.0%) have expected count less than 5. The minimum expected count is .48.
-
(1
6
)
Below are data for car sales for 12 quarters. Interest rates, unemployment numbers
,
and car sales at
Lincoln
Land
Auto are displayed.
QTR INTEREST RATES UNEMPLOYMENT CAR SALES 1 5.6 8.2 300 2 5.7 7.5 290 3 7.8 6 250 4 9.8 6.9 150 5 4.5 5.9 290 6 3.2 4.2 350 7 4.5 5.6 250 8 4.3 4.3 325 9 6.7 6.5 245 10 8.9 7.5 175 11 4.6 7.8 400 12 2.3 5.9 350
Input this data into an SPSS file and then answer the questions as specified .
1 a) (1) What would you r expectations be regarding the relationship between sales and interest rates ? Explain in 2-3 sentences.
1b( (1) What about unemployment and sales ? Explain
2) (1) Which of the three variables is the dependent variable? Explain.
3a) (2) Create a scatter plot between sales and unemployment
The following scatterplot is obtained
3b) (2) Now do the same thing for sales and interest rates.
4 ) (1) Looking at the two scatter plot s, what conclusion do you reach? - (1) Now run a correlation between the three variables(not including quarter)
6) (2) Which independent variable best explains sales ? Be very specific and justify you r answers with data!
7) Based on the best predicting independent variable, run a simple regression.
- (2) Does the model fit at all ? - explain
- (1) W hat per cent of variation does the independent variable explain?
c) (2) Write the regression equation. If you were told that the next quarter interest rates were going to be 7.2 % and unemployment was 6.8 % based on your SIMPLE regression model what would be your forecast of sales.
5. (10) Set up the following data set in SPSS and then answer the questions
An auto manufacturer is trying to improve braking times. Before new engineering was tried a pre-test on braking under various road conditions was conducted. After the changes, a post test was done under similar conditions. A lower score is better. Assume a 95% confidence level. Research is NOT undertaken unless it is assumed the new engineering will help will improve the situation.
| CAR |
Pre-test
seconds |
Post- test
seconds |
|
1.0
2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 |
10.0
10.0 9.0 15.0 10.0 12.0 8.0 13.0 12.0 7.0 9.0 5.0 |
11.0
9.0 11.0 12.0 8.0 10.0 9.0 8.0 11.0 9.0 8.0 6.0 |
- (2) Would you assume a 1 tail or 2 tail test in this case? Explain
- (1) Assuming 11 d.f. what is the critical t for a one tail test ?
- (1) What would be your conclusion be regarding the effectiveness of the new engineering on the brak ing performance. Is it statistically s ignificant?
- (3) Provide 3 pieces of evidence to substantiate your claim.
5) (3) Based on Cohen’s d is there a practical difference? Show calc ulation .
Question 6
. (1
1
)
A university professor wants to emphasize the value of studying in exam performance. The professor gather s data on the amount of time students spend in the library and their scores on a test.
The data is provided below
Set up the data in an SPSS file and then answer the questions
| Student | Library time | Exam Score |
| 1 | 41 | 52 |
| 2 | 30 | 44 |
| 3 | 39 | 48 |
| 4 | 48 | 65 |
| 5 | 55 | 62 |
| 6 | 58 | 60 |
| 7 | 65 | 74 |
| 8 | 80 | 79 |
| 9 | 94 | 80 |
| 10 | 100 | 90 |
| 11 | 120 | 86 |
1) (1) What is the correlation between the exam score s and library time?
2)(2) Is it statistically significant ? - provide evidence.
Run a simple regression with the appropriate dependent and independent variables.
3) (2) Is there evidence that the mo del fits ? Explain with evidence.
4) (2) What percent of variation does the model explain between dependent and independent variables?
5) (2) Write the regression equation for this model.
6) (2)
If library time is 70 minutes predict the point estimate of score of the student.
7. (3) Suppose you want to test the effects of age and education on income (the dependent variable). You want to simultaneous see whe ther each variable impacts income and if there is an interaction between these two independent variables. Based on your experimental design you are able to classify the levels of income into 4 categories and education into 4 categories . What statistical technique would you use and why ? Explain in 3-4 sentences.
8. (5) You are doing an ANOVA study looking at the relationship between performance on a calculus test and the number of math courses taken. Group 1 has 50 people who have taken one course, group 2 -50 who have taken two courses and group 3 -50 that that have taken three . But you get some puzzling results. Someone points out that you have no t controlled for the students prior GPA ’s. In other words , your group s don’t appear to be a random selection of low, middle, and high GPA’s. Assuming you have the information on GPA s but i t is not the primary interest in the study, what statistical procedure might you run next.
9. (1 2 ) We are trying to analyze whether average age at three retirement centers is equal o r different. We do a sample at each center.
The data is as follows:
Center 1 ( n 1 = 22): 60, 66, 65, 55, 62, 70, 51, 72, 58, 61, 71, 41, 70, 57, 55, 63, 64, 76, 74, 54, 58, 73
Center 2 ( n 2 = 18): 56, 65, 65, 63, 57, 47, 72, 56, 52, 75, 66, 62, 68, 75, 60, 73, 63, 64
Center 3 ( n 1 = 23): 67, 56, 65, 61, 63, 59, 42, 53, 63, 65, 60, 57, 62, 70, 73, 63, 55, 52, 58, 68, 70, 72, 45
- (3) Calculate the means, std. deviations for each of the three groups .
- (2) Run an ANOVA -
3) ( 2 ) W hat is the null hypoth esis and alternative hypothesis?
4) (3) What is your conclusion about the null. Provide two pieces specific of evidence to support your conclusion.
5) (2) W hat groups, if any are statistically different using Bonferroni. Cut and paste table and answer question
| Multiple Comparisons | ||||||
|
data
Bonferroni |
||||||
|
(J) center | Mean Difference (I-J) | Std. Error | Sig. | 95% Confidence Interval | |
| Lower Bound | Upper Bound | |||||
| 1 | 2 | -.17677 | 2.63715 | 1.000 | -6.6751 | 6.3216 |
| 3 | 1.90909 | 2.50182 | 1.000 | -4.2558 | 8.0740 | |
| 2 | 1 | .17677 | 2.63715 | 1.000 | -6.3216 | 6.6751 |
| 3 | 2.08586 | 2.63715 | 1.000 | -4.4125 | 8.5842 | |
| 3 | 1 | -1.90909 | 2.50182 | 1.000 | -8.0740 | 4.2558 |
| 2 | -2.08586 | 2.63715 | 1.000 | -8.5842 | 4.4125 | |
10. (4) Complete the following table: for TV TIME EXAMPLE (file has been modified )
| ANOVA | |||||
| TIME IN MINUTES CHILDREN WATCH TV | |||||
| Sum of Squares | df | Mean Square | F | Sig. | |
| Between Groups | 1 | 3 | 23340.750 | 4 | .000 |
| Within Groups | 81516.500 | 2 | 3 | ||
| Total | 151538.750 | 79 | |||
1)____________________________
2)___________________________
3)__________________________
4)_____________________________
11. (14) Complete the following Tables for regression: Based on Convenience stores- modified
| Model Summary | ||||
| Model | R | R Square | Adjusted R Square | Std. Error of the Estimate |
| 1 | .729 a | 1 | .506 | 130.145 |
|
||||
| ANOVA b | ||||||
| Model | Sum of Squares | df | Mean Square | F | Sig. | |
| 1 | Regression | 346256.621 | 1 | 346256.621 | 3 | .000 a |
| Residual | 304878.379 | 18 | 2 | |||
| Total | 651135.000 | 19 | ||||
|
||||||
| b. Dependent Variable: sales | ||||||
| Coefficients a | ||||||
| Model | Unstandardized Coefficients | Standardized Coefficients | t | Sig. | ||
| B | Std. Error | Beta | ||||
| 1 | (Constant) | 331.757 | 109.597 | 3.027 | .007 | |
| traffic | .012 | .003 | .729 | 4 | .000 | |
|
||||||
Complete tables
1)_____________________________
2)___ _ _________________________
3)___ _ ________________________
4)_____ _______________________
Now answer the following questions
5) (2) Does the model seem to fit reasonably well ? Explain with specific evidence.
6) (2) What percent of variation in sales does the model explain? The _____________
7 (3 ) Write the regression equation.
8 (3) If the traffic count is 54,000 what would be the point estimate of the store’s sales ? (show calculation)
Deliverable: Word Document
