In: Statistics and Probability
1. To study the effect of temperature on yield in a chemical process, five batches were produced at each of three temperature levels. The results follow. Temperature 50°C 60°C 70°C 31 30 24 21 31 29 33 34 29 36 23 31 29 27 32 a. Construct an analysis of variance table (to 2 decimals but p-value to 4 decimals, if necessary).
Source of Variation Sum of Squares Degrees of Freedom Mean Square F p-value Treatments 2 0.0 Error 12 Total 14 b. Use a .05 level of significance to test whether the temperature level has an effect on the mean yield of the process. Calculate the value of the test statistic (to 2 decimals).
The p-value is What is your conclusion?
2. In a study conducted to investigate browsing activity by shoppers, each shopper was initially classified as a nonbrowser, light browser, or heavy browser. For each shopper, the study obtained a measure to determine how comfortable the shopper was in a store. Higher scores indicated greater comfort. Suppose the following data were collected.
Light | Heavy | |||
Nonbrowser | Browser | Browser | ||
6 | 7 | 7 | ||
7 | 8 | 9 | ||
8 | 7 | 7 | ||
5 | 6 | 9 | ||
5 | 9 | 6 | ||
6 | 6 | 8 | ||
7 | 8 | 7 | ||
6 | 7 | 9 |
a. Use x=.05 to test for a difference among mean comfort scores for the three types of browsers.
Compute the values identified below (to 2 decimals, if necessary).
Sum of Squares, Treatment | |
Sum of Squares, Error | |
Mean Squares, Treatment | |
Mean Squares, Error |
Calculate the value of the test statistic (to 2 decimals, if necessary).
_____
Use Fisher's LSD procedure to compare the comfort levels of nonbrowsers and light browsers. Use .
Compute the LSD critical value (to 2 decimals). _____
3.
The following data are from an experiment designed to investigate the perception of corporate ethical values among individuals who are in marketing. Three groups are considered: management, research and advertising (higher scores indicate higher ethical values).
Marketing Managers | Marketing Research | Advertising |
10 | 9 | 11 |
9 | 9 | 12 |
8 | 8 | 11 |
9 | 8 | 10 |
10 | 9 | 11 |
8 | 8 | 11 |
a. Compute the values identified below (to 2 decimal, if necessary).
Sum of Squares, Treatment | |
Sum of Squares, Error | |
Mean Squares, Treatment | |
Mean Squares, Error |
b. Use x=.05 to test for a significant difference in perception among the three groups.
Calculate the value of the test statistic (to 2 decimals).
Using , determine where differences between the mean perception scores occur.
Calculate Fisher's LSD value (to 2 decimals).
Difference | Absolute Value | Conclusion |
~x1 - ~x2 | ||
~x1-~x3 | ||
~x2-~x3 |
2)
excel data analysis tool for one factor anova,steps are: write data>menu>data>data analysis>anova :one factor>enter required labels>ok, and following o/p Is obtained,
Anova: Single Factor | ||||||
SUMMARY | ||||||
Groups | Count | Sum | Average | Variance | ||
non browser | 8 | 50 | 6.25 | 1.071429 | ||
light | 8 | 58 | 7.25 | 1.071429 | ||
heavy | 8 | 62 | 7.75 | 1.36 | ||
ANOVA | ||||||
Source of Variation | SS | df | MS | F | P-value | F crit |
Between Groups | 9.333 | 2 | 4.667 | 4.000 | 0.0337 | 3.467 |
Within Groups | 24.500 | 21 | 1.167 | |||
Total | 33.833 | 23 |
a)
Sum of Squares, Treatment | 9.33 |
Sum of Squares, Error | 24.50 |
Mean Squares, Treatment | 4.67 |
Mean Squares, Error | 1.17 |
value of the test statistic =4.00
_____
Level of significance | 0.0500 |
no. of treatments,k | 3 |
DF error =N-k= | 21 |
MSE | 1.167 |
t-critical value,t(α/2,df) | 2.0796 |
Fishers LSD critical value=tα/2,df √(MSE(1/ni+1/nj)) = 1.12
if absolute difference of means > critical value,means are
significnantly different ,otherwise not
for the comfort levels of nonbrowsers and light browsers , absolute mean difference is 1
absolute mean differece = 1 < LSD , so, there is no significant difference
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3)
excel data analysis tool for one factor anova,steps are: write
data>menu>data>data analysis>anova :one factor>enter
required labels>ok, and following o/p Is obtained,
Anova: Single Factor | ||||||
SUMMARY | ||||||
Groups | Count | Sum | Average | Variance | ||
Marketing Managers | 6 | 54 | 9 | 0.8 | ||
Marketing Research | 6 | 51 | 8.5 | 0.3 | ||
Advertising | 6 | 66 | 11.00 | 0.40 | ||
ANOVA | ||||||
Source of Variation | SS | df | MS | F | P-value | F crit |
Between Groups | 21.000 | 2 | 10.500 | 21.000 | 0.0000 | 3.682 |
Within Groups | 7.500 | 15 | 0.500 | |||
Total | 28.500 | 17 |
a)
Sum of Squares, Treatment | 21.00 |
Sum of Squares, Error | 7.50 |
Mean Squares, Treatment | 10.50 |
Mean Squares, Error | 0.50 |
test stat=21.00
b) Fishers LSD critical value=tα/2,df √(MSE(1/ni+1/nj)) = 0.87
population mean difference | critical value | result | |||||
µ1-µ2 | 0.50 | 0.87 | means are not different | ||||
µ1-µ3 | 2.00 | 0.87 | means are different | ||||
µ2-µ3 | 2.50 | 0.87 | means are different |