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Psyc Stats > Exam 4 > Flashcards

Exam 4 Flashcards

1
Q

As degrees of freedom moves away from infinity, t distribution:

a. flattens
b. becomes more normal
c. more closely resembles the z distribution
d. remains the same

A

A: flattens

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2
Q

what is not known when performing single sample t-tests?

a. Sample standard deviation
b. Population mean
c. Sample size
d. All of the above are known

A

D: all the above

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3
Q

the degrees of freedom for single sample t is equal to

a. N
b. N – 1
c. N – 2
d. the population mean

A

N-1

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4
Q

the 99% confidence interval will be __ the 95% confidence interval

a. wider than
b. narrower than
c. the same as
d. none of the above

A

wider than

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5
Q

Which is not true of the sampling distribution of t?
a. It gives all possible different t values for samples of size N
b. It gives the probability of getting each value if sampling is random from the Null
Hypothesis Population
c. It is identical to the z distribution
d. All of the above are true

A

C: identical to z distribution

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6
Q 
With other factors held constant, as the sample size decreases, the width of the confidence
interval will
a. decrease
b. increase
c. remain the same
d. all of the above are possible
A

B: increase

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7
Q

Which of the following are properties of the t distribution?

a. it is a family of many curves that varies with degrees of freedom
b. it is symmetrical
c. it has a mean of 0
d. all of the above are true
e. a and b

A

D: all the above

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8
Q

The independent group design involves analysis of the ______ scores and the repeated
measures design involves analysis of the ______ scores
a. raw; difference
b. raw; raw
c. difference; raw
d. difference; difference

A

A: raw; difference

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9
Q

Which of these is (are) true when using the t-test for correlated groups?

a. The t-test uses information on the direction of the difference scores
b. The t-test uses information on the magnitude difference scores
c. The t-test will be more powerful than the sign test
d. All of the above are true

A

D: all the above

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10
Q

In the t-test for independent samples, there are _____ degrees of freedom

a. n1 – 1
b. n1 + n2 – 2
c. n1 – n2
d. n1 + n2

A

B: n1 + n2 - 2

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11
Q

When conducting a t-test for independent groups, an appropriate non-directional alternative hypothesis would assert that the sample mean difference is due to sampling from a population where

a. µ1 = µ2
b. µ1 = 0
c. µ1≠ 0
d. µ1≠ µ2

A

D: µ1≠ µ2

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12
Q

Which is NOT true regarding assumptions for use of the independent groups t-test?

a. populations from which samples are taken from are normal
b. homogeneity of variance is assumed
c. homoscedasticity is assumed
d. all of the above are true

A

c. homoscedasticity is assumed

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13
Q

In a correlated groups design, the null hypothesis would state that the mean of the sample difference scores are from a population of differences scores where

a. µD= 0
b. µD≠ 0
c. µD= 1
d. None of the above

A

a. µD= 0

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14
Q

What is true about the sampling distribution of F?

a. There are negative values
b. It is negatively skewed
c. It is normal
d. None of the above

A

d. None of the above

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15
Q

What do you need to know about a population when conducting an F test?

a. µ
b. standard dev
c. Neither µ nor standard dev
d. Both

A

C: neither

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16
Q

The alternative hypothesis used in the ANOVA is

a. always non-directional
b. always directional
c. sometimes directional and sometimes non-directional
d. µ1 = µ2 = … = µk

A

a. always non-directional

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17
Q

If Fobt is less than Fcrit, what would you decide?

a. Retain the null hypothesis
b. Accept the alternative hypothesis
c. Reject the null hypothesis
d. Depends on df

A

a. Retain the null hypothesis

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18
Q

SSB + SSW =

a. 1
b. s2T
c. SST
d. Depends on df

A

C. SST

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19
Q

What is the problem with doing multiple t tests between each group of the experiment when there are more than two groups?

a. It is impossible to calculate t in that manner
b. The probability of making a Type I error increases
c. The probability of making a Type II error increases
d. There is no problem

A

b. The probability of making a Type I error increases

20
Q

What does “a priori comparison” mean?

a. Comparisons planned after the experiment has been completed
b. Comparisons planned before the experiment has been completed
c. Multiple comparisons are made
d. The same as post hoc comparison

A

b. Comparisons planned before the experiment has been completed

21
Q

The probability of making one or more Type I errors for the full set of possible multiple comparisons in an experiment is called

a. beta
b. comparison-wise error rate
c. alpha
d. experiment-wise error rate

A

d. experiment-wise error rate

22
Q

One employs a correlated groups design

a. specify calculations eliminate random error
b. eliminate random error
c. reduce effects of individual differences among subjects
d. for prediction

A

C.

23
Q

if a test is a robust test

a. sensitive to its underlying mathematical assumptions
b. doesn’t estimate any population parameters
c. insensitive to its underlying mathematical assumptions
d. may be used despite violations of its underlying mathematical assumptions
e. c and d

A

E

24
Q

independent groups experiment, if we must estimate the population standard dev. to determine the significance of the sample results, the appropriate inference test is the

a. sign test
b. z test
c. t test
d. none of above

A

c

25
Q

students t test for correlated groups really reduces to

a. sign test
b. students t test for single samples using differences scores
c. students t test for independent groups
d. none of above

A

b

26
Q

when analyzing data from experiments that involve more than 2 groups

a. doing t tests on all possible pairs of means increases probability of making type II errors
b. doing t tests on all possible pairs of means increases probability of making type I errors
c. generally permissible to do t tests between all possible pairs of means and use students t distribution
d. doing t tests on all possible pairs of means decreases probability of making type I errors

A

b

27
Q

a priori comparisons

a. are planned in advance of experiment
b. often arise out of theory and prior research
c. may be done w/o obtaining a significant F in the one-way ANOVA
d. all the above

A

d

28
Q

t-test for independent groups, the unbiased estimate of the population variance is

a. weighted avg of s1^2 and s2^2
b. s2^2 alone
c. s1^2 alone
d. none

A

a

29
Q

the one-way ANOVA partitions the total variability into

a. SSw and SSb
b. SSw and SSt
c. Sw^2/MSWithin and SSw
d. Sb^2/MSBetween and SSb

A

a

30
Q

which would cause Fobt to increase?

a. increase in difference between the means
b. increase in the within-groups variability
c. increase in magnitude of the independent variable’s effect
d. a and b
e. a and c

A

e

31
Q

when N is less than infinity, t crit for any alpha level is __ z crit

a. same
b. less than
c. greater than
d. dependent on N

A

c

32
Q

how many t distributions are there?

a. 1
b. 2
c. 30
d. one for each value of df

A

d

33
Q

for a given value of alpha, the critical value of t is __than the critical value of z

a. no different
b. less
c. greater
d. none

A

c

34
Q

as N gets __, the critical value of t gets __

a. larger, larger
b. smaller, smaller
c. larger, smaller
d. smaller, larger
e. both c and d

A

e

35
Q

as N gets infinitely large, the critical value of t equals the critical value of z

a. true
b. false

A

a

36
Q

if the population parameters are known, the t test is __ powerful than the z test

a. more
b. less

A

b

37
Q

s(x bar) is an estimate of __

a. u
b. population standard dev
c. mean of standard dev [o(xbar)]
d. s

A

c

38
Q

in a correlated t test, if the ind. variable has no effect, the sample difference scores are a random sample from a population where the mean difference score (uD)=

a. 0
b. 1
c. N
d. cannot be determined

A

a

39
Q

in analyzing the result of the correlated t test, the __ scores are analyzed

a. standardized
b. normalized
c. raw
d. difference

A

d

40
Q

in the t test for independent groups,

a. we estimate u1 - u2
b. we estimate o^2
c. we estimate s^2
d. df = N-1

A

d

41
Q

as the differences between the group mean increases (rejecting null)

a. Sb^2 increases
b. Fobt decreases
c. Tobt increases
d. none

A

a

42
Q

a major limitation of a 2 group design is that

a. we cant run enough subjects
b. very often, 2 groups are insufficient for a clear interpretation
c. population parameters may not be applicable
d. means between groups may not differ

A

b

43
Q

when analyzing data from experiments that involve more than 2 groups,

a. doing t tests on all possible pairs of means decreases the probability of making type I errors
b. doing t tests on all possible pairs of means increases the probability of making type I errors
c. is it generally permissible to do t tests between all possible pairs of means and use students t distribution
d. doing t tests on all possible pairs of mean increases the probability of making type II errors

A

b

44
Q

which of the following is (are) illegal values for Fobt?

a. 1.00
b. 0.96
c. -2.97
d. b and c

A

c

45
Q

by doing multiple t tests when there are more than 2 experimental groups we increase the risk of making what kind of mistake?

a. accepting the null
b. type I error
c. type II error
d. all the above

A

b

46
Q

type I error is

A

rejecting null when it is true

47
Q

type II error is

A

not rejecting null when the alt hypothesis is true

Psyc Stats (2 decks)

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