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DBS Crashout
DBS Crashout
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1
Which post hoc test is least conservative and most likely to detect a difference?
Tukey’s HSD
Fisher’s LSD
Scheffé
Bonferroni
2
When predictors in a regression model are highly correlated, this is called:
Colinearity Bias
Multicollinearity
Standardization
Homoscedasticity
3
What does the Wilcoxon rank-sum test compare?
Means
Medians
Proportions
Variances
4
What is the purpose of the following image?
it calculates the Chi-square statistic
it computes the t-statistic for comparing two sample means
it used to create a polynomial regression
5
Which regression technique addresses multicollinearity?
ANCOVA
Logistic regression
Ridge regression
Chi-square regression
6
What does a correlation coefficient (r) of 0 mean?
Perfect prediction
The variables are the same
No linear relationship
Strong positive relationship
7
When the sample size is small and data is not normally distributed, which test is preferred?
Chi-square test
Z test
Independent t-test
Wilcoxon rank-sum test
8
What does the Levene test assess?
Whether groups differ in variances
The mean difference between groups
Sample size ratio
Distribution normality
9
What is the most common misuse of correlation?
Using scatterplots
Inferring causation
Applying it to normal data
Using it with interval data
10
What is the purpose of the following formula?
Determine linear regression slope significance
determining effect size in ANOVA
test the significance of a Pearson correlation coefficient
calculate standard error of the mean difference
11
What is the null hypothesis in an independent samples t-test?
The means of the two groups are equal
The two groups are related
The medians of both groups are equal
The variances are unequal
12
In ANOVA, the independent variable is also called:
Covariate
Factor
Level
Treatment
13
Which post hoc test is best for comparing all possible pairs with equal sample sizes?
Bonferroni
Dunnett’s
Tukey’s HSD
Newman-Keuls
14
What does Cohens Kappa statistic tell us?
nothing
The probability of making a Type I error.
How much two independent observers agree with each other
The correlation between two continuous variables
15
What does the F test assess before performing a t-test?
Whether data is nominal
Whether variances are equal
Whether distributions are skewed
Whether medians are equal
16
The t-distribution differs from the z-distribution because it has:
A higher mean
Only negative values
Smaller tails
A wider shape with fatter tails
17
What happens when r is squared and close to zero?
Regression is no longer valid
The relationship is stronger
The predictive value is low
More variance is explained
18
What is the null hypothesis in a one-sample t-test?
The standard deviation is equal
The median equals the hypothesized value
The sample is not normally distributed
The mean equals the hypothesized value
19
The following formulas are for which statistical test?
Chi-square
T-test
ANOVA
20
If you want to control for multiple pairwise comparisons but retain more power than Bonferroni, you should use:
Scheffé
Fisher’s LSD
Dunnett’s
Tukey’s HSD
21
The t-distribution is most appropriate when sample size is:
Smaller than 30
Larger than 100
Exactly 50
More than 1000
22
What does adjusted R^2 account for that regular R^2 does not?
Outliers
Nonlinearity in data
shrinkage
Binary variables
23
If you’re comparing mean step length in your study to a standard value, what type of test would you use?
Chi-square test
Wilcoxon signed-rank test
Two-sample t-test
One-sample t-test
24
The z-test for proportions is appropriate when:
The expected frequency is
The number of successes and failures is at least 5 in each group
Sample sizes are very small
One group is dependent
25
What type of error occurs when we fail to reject a false null hypothesis?
Confidence error
Sampling error
Type I
Type II
26
What type of error occurs when the null hypothesis is true but we reject it?
Confidence error
Sampling error
Type I
Type II
27
A scatterplot with a circular shape suggests:
Strong linear relationship
Correlation is near zero
Nonlinear association
Outliers are present
28
What is the interpretation of r^2 = 0.177?
The correlation is negative
The test is 17.7% significant
17.7% of the variance in Y is explained by X
17.7% of data are outliers
29
What test statistic is used to assess the overall fit in multiple regression?
t-test
z-score
R-test
F-test
30
The Bonferroni test controls for:
Familywise error rate
Type II error
Within-group variance
Effect size
31
The F statistic in ANOVA is a ratio of:
Between-group to within-group variance
Two proportions
Two means
Within-group to total variance
32
Which distribution is used when population standard deviation is unknown and sample size is small?
Z distribution
Normal distribution
Chi-square distribution
T distribution
33
What does the term 'independent groups' mean in a study?
Groups are sampled from different populations
There is only one group
Groups have matched values
One group's data influences the other
34
Which test is the nonparametric alternative to the independent t-test?
Fisher’s LSD
Paired t-test
Wilcoxon rank-sum test
ANOVA
35
When sample sizes are unequal, which ANOVA assumption is most at risk?
Random assignment
Normality
Homogeneity of variance
Independence
36
Comparing correlations across two groups is appropriate when:
The groups are independent
The sample is repeated
Data is non-numeric
The correlation is r = 1
37
Which test allows any type of contrast, not just pairwise?
Dunnett’s
Scheffé’s
Tukey’s
Bonferroni
38
When is it appropriate to reject the null hypothesis in a one-sample t-test?
When p-value
When sample mean equals the hypothesized mean
When the t-value is zero
When p-value > alpha
39
What does the following image represent?
jamovi
standard error of the mean
linear regression slope coefficient
Pearson product moment correlation
40
When would you use ANCOVA?
To analyze a curvilinear relationship
To measure categorical association
To control for confounding while comparing group means
To compare proportions between groups
41
What happens if the standard deviations between two groups are unequal?
t-test remains unchanged
A paired t-test is used
Use a z-test
Use a version of t-test that adjusts for unequal variances
42
What is the main purpose of one-way ANOVA?
Compare means across three or more groups
Compare medians across 3 or more groups
Compare proportions across samples
Compare two group means
43
What is a key limitation of the F test for equal variances?
It requires unequal group sizes
It is sensitive to non-normal data
It can only be used with large samples
It inflates the standard error
44
Which is INCORRECT about one-way ANOVA?
It tests differences in group means
It can handle only two groups
It requires interval or ratio data
It assumes independent observations
45
When is Spearman’s rho more appropriate than Pearson’s r?
For large normally distributed data
When data is ordinal or non-normal
When comparing means
For nominal variables
46
What does the term “Multiple R” represent?
Error variance
Sum of regression coefficients
Correlation between predicted and actual Y values
Correlation between two predictors
47
Which test is most appropriate for comparing multiple groups to a single control group?
Fisher’s LSD
Tukey’s HSD
Dunnett’s test
Scheffé test
48
Which test is the nonparametric version of repeated measures ANOVA?
Friedman test
Kruskal-Wallis test
Mann-Whitney U test
Wilcoxon signed-rank test
49
What does a significant F-test in ANOVA indicate?
All group means are equal
All group sizes are equal
All of the groups means must be different from one another
At least one group mean differs
50
The one-sample t-test is used to compare:
A sample mean to a known or hypothesized population mean
A median to a population variance
A sample median to a known or hypothesized population median
Two group means
51
What does the following image represent?
Familywise Error Rate (FWER)
t statistic
Acquaintancewise Error Rate (AWER)
p-value
52
What does the following image represent?
polynomial regression
your mother
linear regression
Logarithmic regression
53
What is the main assumption of Pearson’s correlation?
Data must be ranked
Joint distribution is bivariate normal
Variables must be nominal
Sample size is below 30
54
What does the upcoming image represent?
z-test formula for large samples
Standard error of the mean
Confidence interval for the mean using the t-distribution
55
What is the primary purpose of multiple regression?
Determine variance in a binary variable
Estimate proportions
Predict a numerical outcome using multiple predictors
Compare three or more group means
56
A Chi-square test outputs an exact p-value.
False
True
57
When comparing two proportions between groups, what test can be used?
Wilcoxon test
Mann-Whitney U
Chi-square test
T-test
58
Which statement about correlation and regression is INCORRECT?
Correlation implies causation
Regression predicts outcomes
Both require linear relationships
Correlation describes relationships
59
What is the key assumption of the independent t-test?
Equal variances
Equal sample sizes
Ordinal data
Paired observations
60
What does Tukey’s HSD stand for?
Homogeneous Sample Difference
Highly Significant Difference
High Statistical Difference
Honestly Significant Difference
61
What does the following image represent?
expected frequency in a Chi-square test
the mean of a data set
degrees of freedom for a Chi-square test
62
What does the Fisher’s z transformation allow researchers to do?
Test correlations and compare them
Convert ranks to z-scores
Visualize skewness
Test for normality
63
Which of the following is true about Kruskal–Wallis test?
It assumes equal standard deviations
It is used when ANOVA assumptions are met
It is a nonparametric alternative to ANOVA
It is a parametric alternative to ANOVA
64
What is the t-test for correlation used to test?
Whether the slope equals 1
Whether the correlation equals 0
Whether r is exactly 1
Whether variables are independent
65
Newman-Keuls differs from Tukey’s HSD because it:
Does not compare means
Is more conservative
Uses nonparametric statistics
Uses unequal alpha levels across comparisons
66
Which of the following compares independent proportions?
Fisher’s exact test
One-way ANOVA
McNemar’s test
Paired t-test
67
What is the coefficient of determination?
r^2, representing explained variance
The residual sum of squares
The standard error of correlation
The confidence interval of r
68
What does a p-value tell us?
Whether the test is two-tailed or one-tailed
How likely the null hypothesis is true
How likely the observed result occurred by chance
The variance in the population
69
Fisher’s LSD is best used when:
You are using a chi-square test
Multiple dependent variables are involved
Only a few comparisons are planned
The F-test is not significant
70
Real or Ai?
Ai
Real
71
What is the main risk of multicollinearity in regression models?
Inflated standard errors
Lower adjusted R^2
Larger sample size
Reduced variability
72
What does a 95% confidence interval mean?
There's a 95% chance of Type II error
The sample mean lies within the interval 95% of the time
95% of all possible intervals would contain the true population mean
The population mean has a 95% chance of falling in the sample
73
Which of the following affects the width of a confidence interval?
The degrees of freedom only
Whether the test is one-sided or not
Sample variance and sample size
Number of tails in test
74
What is the role of cross-validation in model building?
Increase p-values
Test model reliability on new data
Normalize predictors
Eliminate outliers
75
If the group means are not very different, the F value is likely to be:
Zero
Near 1
High
Negative
76
Which is INCORRECT about stepwise regression?
Keeps only statistically significant variables
Can be used in medical studies
Always gives the same result as forward selection
Combines forward and backward selection
77
If BMI and % body fat have an r of 0.42, what does this mean?
Moderately strong correlation
Weak correlation
Strong correlation
Very Weak correlation
78
Which of the following is an assumption of ANOVA?
Population variances are equal
All medians are equal
Observations are paired
Sample variances are equal
79
Which post hoc test is known to be the most conservative?
Scheffé
Fisher’s LSD
Tukey’s HSD
Bonferroni
