Week 4 - Statistical models (correlations and t-tests)

Question 1

Error in statistical models…
a. Purely reflects measurement error
b. Is only apparent on rare occasions
c. Is typically ignored
d. Is important to measure, report and interpret

Answer 1

d. Is important to measure, report and interpret

Question 2

What three factors affect statistical power?
a. Sample size, effect size, type 1 error rate
b. Sample size, statistical significance, type 1 error rate
c. Sample size, statistical significance, independence
d. Sample size, effect size, independence

Answer 2

b. Sample size, statistical significance, type 1 error rate

Question 3

Data = x + y, where x and y are…
a. Model and error
b. Distribution and model
c. Variance and error
d. Variance and distribution

Answer 3

a. Model and error

Question 4

What is not a step in Null Hypothesis Testing?
a. Formulate an interpretation of the data before analysis
b. Assess the “statistical significance” (p value) of the result
c. Collect some data relevant to the hypothesis
d. Formulate a hypothesis that embodies our prediction

Answer 4

a. Formulate an interpretation of the data before analysis

Question 5

The probability (p) value is…
a. The probably that if you ran the study again, you would obtain the same result that % of the time
b. The probability of the null hypothesis being true
c. The probability that you are making the wrong decision
d. Under the assumption that the null hypothesis is true, the probability of getting a sample as or more extreme as our own

Answer 5

d. Under the assumption that the null hypothesis is true, the probability of getting a sample as or more extreme as our own

Question 6

What is an appropriate way to report a statistical model?
a. The effect approached significance
b. There was a trend for significance
c. The effect was nearly significant
d. The effect was statistically significant

Answer 6

d. The effect was statistically significant

Question 7

The alpha value is…
a. Set before analyses are run
b. Akin to the p value
c. Always 0.05
d. An alternative measure of effect size

Answer 7

a. Set before analyses are run

Question 8

Type 1 errors reflect x, and type 2 errors reflect y. What are x and y, respectively?
a. They both reflect false positives
b. They both reflect false negatives
c. False positives and false negatives
d. False negatives and false positives

Answer 8

c. False positives and false negatives

Question 9

Effect size is a measure of…
a. The significance of the effect
b. The variability of the effect
c. The error of the effect
d. The strength of the effect

Answer 9

d. The strength of the effect

Question 10

Statistical significance is not…

a. Determined by comparing the p-value with the alpha value
b. Based on a relatively arbitrary cut-off point
c. A dichotomous assessment
d. A measure of effect size

Answer 10

d. A measure of effect size

Question 11

Which test is parametric?
a. Pearson correlation
b. Spearman correlation
c. Wilcoxon test
d. Kruskall-wallis test

Answer 11

a. Pearson correlation

Question 12

In relation to the hypothesis, ‘In a mirror drawing task participants will trace a star figure faster (measured in seconds) on the trials in which they used their dominant hand than on the trials in which they used their non-dominant hand’
What is the inferential statistical test of choice?
a. Paired samples t-test
b. Independent samples t-test
c. Pearson Correlation
d. ANOVA

Answer 12

a. Paired samples t-test

Question 13

A statistical model uses ____ to summarise a dataset relative to ___:?
a. Statistics, a single variable
b. Maths, a single variable
c. Statistics, multiple variables
d. Maths, multiple variables

Answer 13

d. Maths, multiple variables

Question 14

in relation to the hypothesis, ‘Intellectually disabled adolescents given different types of skills training programs (Group 1=Social Skills, Group 2=Daily Living Skills, Group 3=Both Social Skills and Daily Living Skills) will differ in their level of Assertiveness (measured on the Goldberg Assertiveness Scale).’
What is the inferential statistical test of choice?
a. Oneway ANOVA
b. Independent samples t-test
c. Pearson Correlation
d. Paired samples t-test

Answer 14

b. Independent samples t-test

Question 15

You should construct a scattergram before conducting a Pearson correlation because
a. it tells you whether the result is significant or not
b. there is no point in computing the correlation unless you can see a clear line formed on the graph
c. there are different procedures depending on whether there appears to be a positive or a negative correlation
d. you should not conduct a Pearson correlation if you see a clear curvilinear relationship

Answer 15

d. you should not conduct a Pearson correlation if you see a clear curvilinear relationship

Question 16

in relation to the hypothesis, ‘There is a relationship between blood pressure and heart rate.’
What is the inferential statistical test of choice?
a. Paired samples t-test
b. Independent samples t-test
c. Pearson Correlation
d. Anova

Answer 16

c. Pearson Correlation

Question 17

We say that a correlation is significant if…
a. the dots appear to form a straight line on the scattergram
b. there is less than 5% probability that we could have obtained a correlation this strong or stronger if the null hypothesis is true
c. r<.05
d. it accounts for a large proportion of the variance

Answer 17

b. there is less than 5% probability that we could have obtained a correlation this strong or stronger if the null hypothesis is true

Question 18

A researcher aims to compare the effects of concussions between horse riders and skiers. What statistical test would you expect them to use?

a. ANOVA
b. Within-subjects t-test
c. Correlation
d. Independent t-test

Answer 18

Independent t-test

Question 19

A Pearson correlation assesses what type of relationship between two factors?

a. Non-linear
b. Quadratic
c. Linear
d. Sinusoidal

Answer 19

Linear

Question 20

You have two continuous and normally distributed variables. What should you use to assess the relationship between the two variables?

a. Pearson’s correlation
b. Spearman correlation
c. ANOVA
d. T-test

Answer 20

Pearson’s correlation

Question 21

You run a correlation and the result is r=0.16, p=.015, n=231. You have an alpha of 0.05. What does it mean?

a. There is a non-significant positive relationship between the two variables, with a negligible to small effect size
b. There is a statistically significant negative relationship between the two variables, with a negligible to small effect size
c. There is a statistically significant positive relationship between the two variables, with a negligible to small effect size
d. There is a non-significant negative relationship between the two variables, with a negligible to small effect size

Answer 21

There is a statistically significant positive relationship between the two variables, with a negligible to small effect size

Question 22

You want to know if there is a significant difference in test scores between two different schools, School A and School B. You collect test scores from a random sample of students from each school and use a(n) _______________ to determine if the mean scores are significantly different.

Answer 22

Independent t-test

Question 23

You’re testing the effectiveness of a new memory-enhancing drug. You measure the memory scores of the same group of participants before and after taking the drug. You use a(n) ___________ to determine if there is a significant improvement in memory after taking the drug.

Answer 23

Paired t-test

Question 24

You want to investigate if there’s a relationship between the number of hours students spend studying for an exam and their final exam scores. You collect data on hours studied and exam scores for a group of students and use _______________ to measure the strength and direction of this relationship.

Answer 24

Pearson’s correlation coefficient