Inferential statistics

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QUESTION 1

1. In an ANOVA, what are the degrees of freedom for the following output:

ANOVA
Source of Variation	SS	df	MS	F	P-value	F crit
Between Groups	71.64921	2	35.8246	2.503716	0.115279	3.68232
Within Groups	214.6286	15	14.30857

Total	286.2778	17

		2, 15
		2, 17
		2.50
		17

5 points

QUESTION 2

1. Males and females were compared for the mean number of smiles during a five-minute interview. The 30 males' mean was 3.62 and the 24 females' mean was 5.04. An α level of .05 was adopted and an F = 4.02 was obtained. What conclusion is appropriate?

		males smile more than females
		females smile more than males
		the null hypothesis should be retained
		none of the choices are correct

5 points

QUESTION 3

1. The one way ANOVA is not appropriate if the data come from

		neither choice is correct
		both choices are correct
		populations that do not have the same mean
		paired-samples design;

5 points

QUESTION 4

1. The null hypothesis in an ANOVA problem is that

		one or more of the groups was drawn from a different population;
		none of the groups were drawn from the same population;
		any of the other alternatives, depending on how many levels of the independent variable there are.
		all the groups are drawn from the same population;

5 points

QUESTION 5

1. When the F value in the F table is smaller than the F value calculated from the data

		reject the null hypothesis;
		none of the choices are correct
		retain the null hypothesis;
		reject or retain the null hypothesis, depending on how far apart the group means are;

5 points

QUESTION 6

1. A researcher conducted a paired sample t-test to determine if advertisements were viewed more in the morning (before noon) or in the evening (after 5pm) for eight different universities. The results were as follows:

	Morning	Evening
	Morning	Evening
Mean	32	40.625
Variance	89.71428571	504.5536
Observations	8	8
Pearson Correlation	0.343785438
Hypothesized Mean Difference	0
df	7
t Stat	-1.152587077
P(T<=t) one-tail	0.143458126
t Critical one-tail	1.894578605
P(T<=t) two-tail	0.286916252
t Critical two-tail	2.364624252

Is there a significant difference between morning and evening access to the university advertisements?

		Yes, there was a significant difference between Morning (M= 32), and Evening (M=40.625), (t [7] = 1.15 p < .05).
		No, there was no difference between Morning (M= 32), and Evening (M=40.625), (t [7] = 1.15, p < .05).
		No, there was no difference between Morning (M= 32), and Evening (M=40.625), (t [7] = 1.15, p > .05).
		Yes, there was a significant difference between Morning (M= 32), and Evening (M=40.625), (t [7] = .28, p < .05).

5 points

QUESTION 7

1. p < .01 means that the

		the results are significant
		neither choice is significant
		the null hypothesis should be rejected
		both choices are correct

5 points

QUESTION 8

1. In an independent samples design, the Dog's mean was 54.0 and the Cat's mean was 53.9. Larger scores are better. A t value of 2.50 was calculated and an α level of .05 adopted. Which conclusion is appropriate with a 2-tailed test?

		If df = 5, Dogs are significantly better than Cats
		If df = 9, Dogs are not significantly different from Cats
		If df = 10, Dogs are significantly better than Cats
		If df = 4, Cats are significantly better than Dogs

5 points

QUESTION 9

1. p < .05 means that the difference between sample means

		none of the choices are correct
		the results should be declared "not significant";
		both choices are correct
		should be attributed to chance rather than to the independent variable

5 points

QUESTION 10

1. With an acknowledgment to Sesame Street, "Which of these things is not like the others, which of these things doesn't belong?"

		matched pairs
		natural pairs
		repeated measures
		independent samples

5 points

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