stats final
For a given value of alpha, the critical value of t is _______ than the critical value of z.
greater
As N gets infinitely large, the critical value of t equals the critical value of z.
true
If H0 is false, as the power of the experiment increases, the probability of rejecting H0 increases.
true
In an independent groups design, if the independent variable has a real effect, µ1 ≠ µ2.
true
As the df increases, the t distribution _________.
approaches the normal distribution
If the alpha level is changed from 0.05 to 0.01, what effect does it have on beta?
beta increases
If the alpha level is changed from 0.05 to 0.01, what effect does this have on beta?
beta increases
Data analysis involving statistical inference basically involves _________.
calculating the appropriate statistic and evaluating the statistic based on its sampling distribution
If you reject H0 when H0 is false, you have made a _________.
correct decision
With other factors held constant, as the effect of the independent variable decreases, power will _________ and the probability of a Type II error will _________.
decrease, increase
The sampling distribution of t depends on _________.
df
Which of the following is(are) true?
df for MSbetween = k − 1 AND df for MSwithin = N − k AND dftotal = N − 1
In analyzing the results of the correlated t test, the _________ scores are analyzed.
difference
| tcrit | for any alpha level is _________ | zcrit | for N less than infinity.
greater than
An alpha level of 0.05 indicates that _________.
if H0 is true, the probability of falsely rejecting it is limited to 0.05
The one-way ANOVA partitions the total variability into _________.
SSwithin and SSbetween
If alpha is 0.05 and obtained probability level is 0.01, you could be making a _________.
Type I error or a correct decision
The use of the t test for independent groups assumes _________.
X1-X2 is normally distributed and s12 = s22
If you retain the null hypothesis, you may be making _________.
a Type II error and a correct decision
If the alternative hypothesis states that alcohol affects short-term memory, the null hypothesis states _________.
alcohol has no effect on short-term memory
The sampling distribution of the mean gives _________.
all the values the sample mean can take and the probability of getting each mean value if sampling is random from the H0 population
Which of the following may be false?
alpha + beta = 1
The alpha level _________.
is determined by the consequences of making a Type I and Type II error
Maximizing the power of an experiment _________.
minimizes beta
In the t test for independent samples, there are _________ degrees of freedom.
n1 + n2 - 2
Pnull _________.
never equals 0.50
Sx is an estimate of _________.
o- x
The alternative hypothesis evaluated by Fobt in the one-way ANOVA states that _________.
one or more of the conditions have different effects
If H0 is in reality false and it is legitimate to use a directional H1, which of the following will yield a more powerful test?
one-tailed alternative hypothesis
In an experiment involving a nondirectional alternative hypothesis, the obtained result was 7 pluses and 1 minus. To evaluate the null hypothesis, which of the following probabilities would you use?
p(0) + p (1) + p(7) + p(8)
The sample mean is an example of _________.
point estimation
If the null hypothesis is false, the probability of making a correct decision is given by _________.
power
With alpha and N held constant, as the effect of the independent variable increases _________.
power increases
A researcher believes that women today weigh less than in previous years. To investigate this belief, she randomly samples 41 adult women and records their weights. The scores have a mean of 111 lbs. and a standard deviation of 12.4. A local census taken several years ago shows the mean weight of adult women was 115 lbs. Using a = 0.011 tail, the critical value of the appropriate statistic for testing H0 is _________.
-2.423
The mean of the t distribution equals _________.
0
The mean attention span for adults in a certain village is 15 minutes with a standard deviation of 6.4. What is the probability of randomly selecting a sample of 30 scores from this population that has a mean attention span equal to or greater than 17 minutes?
0.0436
If H0 is true and the probability of making a Type I error is 0.05, then the probability of making a correct decision is _________.
0.95
The mean attention span for adults in a certain village is 15 minutes with a standard deviation of 6.4. If the means of all possible samples of size 30 is taken from this population, o- x will equal _________.
1.17
The 95% confidence interval of the mean for X= 13.0, s = 1.6, and N = 21 is _________.
12.27 to 13.73
If SStotal = 20 and SSbetween = 14, SSwithin = _________.
6
An English teacher has been teaching a sixth grade composition class for many years. He has the feeling that over the past several years, the writing ability of students has changed. A national test of proficiency in composition was administered 5 years ago. The resulting distribution of scores was normally shaped, had a mean of 85 and a standard deviation of 10.9. In order to test his feeling, he gives his present class of 43 students the same proficiency test. The resulting mean is 80 and the standard deviation is 8.7. Using the z test with á = 0.052 tail, what is your conclusion?
reject H0; the present class appears deficient in composition writing
If alpha equals 0.05 and the probability level of your experiment is 0.04, you would _________.
reject the null hypothesis
The Null Hypothesis Population is an actual or theoretical set of population scores that would result if _________.
the experiment were done on the entire population and the independent variable had no effect
The advantage of a powerful experiment is that _________.
you are more likely to detect the real effects of the independent variable, if there are any.
For which of these tests do you need to know the sampling distribution of the relevant statistic in order to use the statistic for hypothesis testing?
z test, t test, and sign test
To use the z test, _________.
µ and s must be specified and the sampling distribution of X should be normal
The null hypothesis in the one-way ANOVA asserts that _________.
µ1 = µ2 = µ3 = µk and the between group variance estimate and the within group variance estimate are both estimates of the same population variance
Using the t test for independent groups, a directional alternative hypothesis predicts _________.
µ1 > µ2 or µ1 < µ2, depending on the direction
The mean of the sampling distribution of X1-X2= _________.
µ1 − µ2
When analyzing data from experiments that involve more than two groups _________.
doing t tests on all possible pairs of means increases the probability of making Type I errors
The area under the critical region for rejection must _________.
equal alpha
Increasing N affects the magnitude of the effect of the independent variable.
false
The t test is more sensitive than the z test.
false
The z test does not depend on the shape of the sampling distribution of X.
false
The mean attention span for adults in a certain village is 15 minutes with a standard deviation of 6.4. The mean of all possible samples of size 30, taken from that population equals _________.
15
Which of the following is(are) illegal values for Fobt?
-2.97
You are considering testing a new drug that is supposed to facilitate learning in mentally retarded children. Because there is relatively little known about the drug, you plan to use a nondirectional alternative hypothesis. Since your resources are limited, you can test only 15 subjects. The subjects will be run in a repeated measures design and the data will be analyzed with the sign test, using a = 0.052 tail. If the drug has a medium effect on learning such that Preal = 0.70, what is the probability you will detect the effect when doing your experiment.
0.2969
If dfbetween = 2 and dfwithin = 14, using a = 0.05, Fcrit = _________.
3.74
The _______ confidence interval for the population mean is always wider than the _______ confidence interval for the population mean.
99%, 95%
As the differences between the group means increases, _________.
MSbetween increases
Which of the following values of P represents the largest effect?
Preal = 0.20
In the t test for independent groups, the unbiased estimate of the population variance 2 is _________.
a weighted average of s12 and s22 AND (SS1 + SS2)/(n1 + n2 − 2)
If H0 is true, then the probability of rejecting H0 is limited by _________.
alpha
In order to calculate power you must know _________.
alpha, N and P
A raw score distribution that is negatively skewed will produce a sampling distribution of the mean for N = 4 which is _________.
also negatively skewed
The alternative hypothesis for which Fobt is appropriate in the one-way ANOVA is _________.
always nondirectional and never nondirectional
Which of the following would cause Fobt to increase?
an increase in the difference between the means and an increase in the magnitude of the independent variable's effect
If the variability of the raw score population increases and N is held constant, o- x _________.
increases
The power of the t test increases with _________.
increases in the effect of the independent variable, increases in N, and decreases in the sample variance(s)
Which of the following increase(s) the power of the t test?
increasing N and increasing the effect of the independent variable
The sampling distribution of the mean _________.
is normally distributed if the population raw scores are normally distributed and is considered normally distributed if N > 300
Which of the following is (are) true about the F distribution?
it has no negative values, it is positively skewed and there are a family of F curves uniquely determined by df(numerator) and df(denominator)
If a test is a robust test,
it is insensitive to its underlying mathematical assumptions and it often may be used despite violations of its underlying mathematical assumptions
A researcher believes that women today weigh less than in previous years. To investigate this belief, she randomly samples 41 adult women and records their weights. The scores have a mean of 111 lbs. and a standard deviation of 12.4. A local census taken several years ago shows the mean weight of adult women was 115 lbs. What do you conclude, using the appropriate inference test and α = 0.011 tail?
retain H0
In a correlated groups experiment, if we must estimate the population standard deviation to determine the significance of the sample results, the appropriate statistical test is _________.
t test
Which of the following tests analyzes the difference between the means of two independent samples?
t test for independent groups
A major advantage to using a two condition experiment (e.g. control and experimental groups) is _________.
the experiment does not need to know population parameters
When the results of an experiment are nonsignificant, the proper conclusion(s) is (are) _________.
the experiment fails to show a real effect for the independent variable
The nondirectional alternative hypothesis asserts that _________.
the independent variable has an effect
lf alpha is changed from 0.05 to 0.01, _________.
the probability we will retain a false H0 increases
The parameter being estimated in the analysis of variance is the ________.
variance of the H0 populations
The t test differs from the z test in that _________.
with the t test we estimate s and the t distribution is a family of curves
In an independent groups design the nondirectional alternative hypothesis states _________.
µ1 ?0? µ2
The null hypothesis for a nondirectional H1 using the t test for correlated groups asserts that _________.
µD = 0
Which of the following are true?
µx is the mean of the sampling distribution of the mean
If we take all possible samples from a normally distributed population, which of the following sample sizes will yield the smallest variation in the means of the samples?
120
The sampling distribution of a statistic _________.
gives all the values a statistic can take, is a probability distribution, and gives the probability of getting each value of a statistic under the assumption it had resulted due to chance alone
When using the t test, we reject H0 _________.
if | tobt | ≥ | tcrit |
The t test assumes that the independent variable affects the _________ of the populations.
means
In stating H0 and H1, one must be certain that they are _________.
mutually exclusive and exhaustive
"Degrees of freedom" for any statistic is defined as _________.
the number of scores that are free to vary in calculating the statistic
It is impossible to ever prove that H0 is true because _________.
the power to detect very weak but real effects of the independent variable is always low
The 95% confidence interval arrived at from a particular experiment is 72-79. This means that _________.
the probability is 0.95 that the interval 72-79 contains µ
Power is defined as ______.
the probability of rejecting H0 if H0 is false and the probability of accepting H1 if H1 is true
Which of the following is (are) assumption(s) underlying the use of the F test?
the raw score populations are normally distributed and the variances of the raw score populations are the same
The t test for correlated groups requires that _________.
the sampling distribution of D is normally is normally distributed
The proper use of the t test requires that _________.
the sampling distribution of X is normal or N ≥ 30
Which of the following are assumptions underlying the use of the t test for independent groups?
the sampling distribution of X1-X2 must be normal and the samples are drawn from populations having equal variances
Confidence limits are defined as _________.
the values that bound the confidence interval
The F ratio increases as _________.
the variability between means increases relative to the variability within groups
If SStotal = 96, SSwithin = 47, and SSbetween = 68, what would you conclude?
there must be an error in the calculations
Which of the following increase(s) as the difference between the group means increases?
tobt AND MSbetween AND Fobt
The sampling distribution of the mean varies with the size of the sample.
true