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WorksheetsStats- Exam review (post test 1)
Total questions: 42
Worksheet time: 23mins
The outcome data for a t-test must be continuous
true
false
A type 1 error occurs:
every time the null hypothesis is rejected
when a researcher fails to reject a false null hypothesis
when a true null hypothesis is rejected
when the alternative hypothesis is rejected even though it's true
If we predict that an intervention will improve performance, the critical region for a 1-tail test would be on the right hand of the distribution
true
false
For the one-sample t-test, the population's standard deviation (sigma) is:
unknown
known
equal to sample SD
greater than sample sd
A researcher reports a t statistic w/ df= 20. How many individual participants were involved in the study?
19
20
21
none of the above
A hypothesis test (n=25, two-tailed) is used to evaluate the effect of a treatment. The hypothesis test results in a z-score of z = 2.37
reject Ho w/ a= .05, but not a = .01
reject Ho w/ either a =.05 or a= .01
Fail to reject Ho w/ either alpha level
cannot answer w/out additional info
The data for a repeated-measures study consists of 2 scores/person, but the mean and variance are calculated w/ 1 score each per person
true
false
A researcher reports t(12)= 2.86, p < .05 for a repeated-measures research study. How many individuals participated in the study?
n=11
n=13
n=24
n25
If an independent-measures t statistic has df= 20, then there were a total of 18 individuals participating in the research study?
true
false
An independent-measures study uses two samples, each w/ n=12, if the data produce t= 2.50, then what is the correct decision for a two-tailed test?
reject the null w/ a=.05, but fail to reject w/ a=.01
reject the null w/ either alpha level
fail to reject the null w/ either alpha level
cannot answer question w/out additional info
In testing for differences between the means of two independent populations, the null hypothesis is:
H1: μ1 - μ2 =0
Ho: μ1 - μ2 < 0
H1: μ1 - μ2 < 0
Ho: μ1 - μ2 =0
To test if there are differences in average prices between 2 supermarkets, we randomly pick six items from each and compare. We should use the:
one-sample t-test
two-sample t-test
repeated measures/paired tests
none of these options
Chi-square is a statistical procedure used to test a hypothesis about categorical data
true
false
The value of chi-square
is equal to the square root of F
can be either + or -
will always be positive
will always be negative
The critical value for a chi-square test decreases if the number of categories is decreased
true
false
The degrees of freedom in a chi-square goodness of fit test are based on the number of response categories rather than sample size
true
false
Kelly is interested in whether yr in college (freshman, sophomore, junior, senior) is related to whether students work (y or n)- if a=.05, the crit value is?
5.991
7.815
9.488
15.507
Which of these scenarios would be best analyzed using a chi-square test of independence?
examining the distribution of grades in a class
testing whether males or females have a higher mean anxiety score
testing whether more males or females drink coffee- yes or no
testing a nutrition program's impact on mean weight in diabetic patients
If the 95% CI includes 0, the null hypothesis can be rejected
true
false
When something is statistically significant, this means that it is always clinically meaningful or a significant change
false
true
When we fail to reject the null, we say that the probability is (a) than the alpha level of the test
Which of the following is an example of a null hypothesis in a t-test w/ 1 sample?
Ho: mu = 35
Ho: mu DNE 35
Ho: mu 1 - mu 2 = 0
Ho: mu 1 > mu 2
It is (a) to reject the null when a = .01
What is the primary purpose of ANOVA?
comparing means across 3/3+ groups
comparing medians across 3/3+ groups
examining the relationship between two categorical variables
identifying normally distributed data
ANOVA can only be used on variables where the means can be calculated, thus it may be used when the outcome variables are categorical
true
false
The null hypothesis for one-way ANOVA states that all means are equal
true
false
On average, what value is expected for the f-ratio if the null hypothesis is true?
0
1
k-1
N-k
A study reported an F-ratio w/ df = 2, 36. How many treatments were compared in the study and what was the total number of participants?
2 treatments; 37 participants
2 treatments; 38 participants
3 treatments; 38 participants
3 treatments, 39 participants
Post-hoc tests tell us which group means are significantly different from other group means
true
false
The correlation coefficient is used to determine:
the value of the y-variable given a specific value of the x-variable
a value of the x-variable given a specific value of the y variable
strength and direction of relationship between the x and y variables
none of these
The Pearson correlation is calculated for a sample of n=25. What df value should be used to determine whether or not the correlation is significant?
23
24
25
cannot be determined w/out additional info
For a sample of n=20, at least how large a Pearson correlation is necessary to be statistically significant for a two tailed test w/ a= .05?
0.444
0.433
0.423
0.413
A set of n=5 pairs of X and Y values has SSx = 4, SSy = 16, and SP =8. For these data, what is the Pearson correlation?
r= 8/20
r=8/√20
r= 8/264
r= 8/8
A negative correlation between X and Y implies that if X decreases then Y increases?
true
false
If there is a negative correlation between X and Y, then the regression equation, Y=bX + a will have:
b > 0
b < 0
a > 0
a < 0
The following scores were made by a student on 5 tests:
Test 1: Score= 20, mean=15, SD=3
Test 2: Score= 500, mean=500, SD=100
Test 3: Score= 30, mean=25, SD =10
Test 4: Score=100, mean=100, SD=16
Test 5: Score=35, mean=28, SD=3
Relative to the mean and SD, the highest score was made on:
test 1
test 2
test 3
test 4
test 5
A 6-sided die is rolled twice. What is the probability that the first roll will come up 1 and the second 2?
1/6
2/6
1/36
2/16
Suppose the correlation between height and weight for adults is .70. What percent of the variability in the data is due to the relationship between height and weight? In other words, what percentage of variance in height is predicted from weight?
30%
35%
49%
70%
NONE OF THE ABOVE
The correlation between variables A and B is .68. The correlation between variables A and C is -.74. Is variable A more closely related to variable B or C?
Variable B
variable c
Assume you have a set of 100 scores w/ a mean of 80 and SD of 20. What is the 95% confidence interval for this data?
(a)
A researcher analyzes data in SPSS, and gets a pearson correlation of .991. What can you conclude about the relationship between the speed a vehicle travels (X) and the distance required to stop (Y)?
strong, negative relationship between car speed and stopping distance
weak, positive relationship between car speed and stopping distance
strong, positive relationship between car speed and stopping distance
weak, negative relationship between car speed and stopping distance
What is the coefficient of determination (r-squared) value of r=.991
r2= 0.67, 67% of the variation in stopping distance is explained by speed
r2= 0.98, 98% of the variation in stopping distance is explained by speed
r2= 0.99, 99% of the variation in stopping distance is explained by speed
r2=0.97, 87% of the variation in stopping distance is explained by speed
