Question

An investigator wishes to conduct a test of the effect of alcohol consumption on the performance of automobile drivers, possibly to gain more information about the legal maximum for DUI arrests. Before the driving test, subjects drink a glass of orange juice laced with controlled amounts of vodka. Their performance is measured by the number of errors on a driving simulator. Five subjects are randomly assigned to each of five groups receiving different amounts of vodka (either 0, 1, 2, 4 or 6 ounces), and the following results were obtained: DRIVING ERRORS AS A FUNCTION OF ALCOHOL CONSUMPTION (OUNCES)

ZERO ONE TWO FOUR SIX

1 4 6 15 20

1 3 1 6 25

3 1 2 9 10

6 7 10 17 10

4 5 7 9 9

Total: 15 20 26 56 74

SumX= G= 191 SumX2 = 2371

A) Using SPSS, conduct an ANOVA, including post hoc tests if necessary.

B) Using either h2 or Coen’s d, calculate effect size. What kind of effect does this indicate?

C) What, in plain English, does all this mean?

Answer 1

NULL HYPOTHESIS H0:

ALTERNATIVE HYPOTHESIS Ha: At least one mean is not equal

alpha=0.05

From above anova table

p value= 0.001<0.05 therefore significant hence reject null hypothesis and conclude that at least one mean is different.

From above analysis

there is significant difference between zero ounces and six ounces and one ounces and six and ounces.

b) eta squared= treatment sum of squares/total sum of squares

= 523.360/911.760

eta squared= 0.574

57.4% of the variance in the Dependent Variable is due to the Independent variable.