Quantitative Methods

Question 1

When is an independent samples T-test used?

Answer 1

Used to determine if the mean differs significantly between 2 populations

Question 2

When is a paired T-test used?

Answer 2

When samples are linked with each other e.g. heart rate before and after exercise

Question 3

What does Mann-Whitney tell us?

Answer 3

(Non-parametric) Are two independent population medians different?

Question 4

What does Wilcoxon signed ranks test tell us?

Answer 4

(Non-parametric) Are paired sample values different

Question 5

What do ANOVA and linear regression both require to be used?

Answer 5

Normal residuals and equal variances (or sphericity for >2 levels)

Question 6

What tests for normality are used?

Answer 6

Kolmogorov-Smirnov

Shapiro-Wilk

Question 7

What is the difference between a One-way ANOVA and a Two-way ANOVA?

Answer 7

They either have one or two independent variable

Question 8

How to test for sphericity?

Answer 8

Use Mauchly’s test of sphericity

Question 9

When do you need to test for sphericity?

Answer 9

When doing a repeated measures ANOVA

Question 10

What to do if sphericity is not assumed?

Answer 10

Use Greenhouse-Geisser or Huynh-Feldt

Question 11

Assumptions of regression

Answer 11

• Residuals are normally distributed
• Error variance of y is equal across the range of predicted y-values
• The relationship is linear
• No relationship between the residuals and the X and Y variables

Question 12

What is a Levene’s test?

Answer 12

Used to test for equality of variants before carrying out a T-test or ANOVA

Question 13

What is Pearson’s correlation also known as?

Is it parametric or nonparametric?

Answer 13

Pearson’s product moment correlation coefficient (PARAMETRIC)

Question 14

What is Pearson’s correlation?

Answer 14

Ranges from -1 (perfect negative correlation) to 1 (perfect positive correlation)
A value of 0 indicates that there is no association between variables

Question 15

What is the non-parametric version of Pearson’s correlation coefficient?

Answer 15

Spearman rank correlation

Question 16

What is the difference between a univariate and multivariate statistical test?

Answer 16

For a univariate test, you test only a single response variable but for a multivariate test, you examine two or more response variables

Question 17

What is a One Sample T-test?

Answer 17

Tests whether or not the mean of a set of values you collected is significantly different to a fixed value

Question 18

What is the non-parametric version of the One-Sample T-test?

Answer 18

Wilcoxon matched-pair signed-tank test

Question 19

What is the non-parametric equivalent of ANOVA?

Answer 19

Kruskal-Wallis test

Question 20

What is a Bonferroni correction?

Answer 20

Carried out when you do multiple tests with a chance of getting false positives. Multiply any p-values you obtain by the number of tests you perform

Question 21

When to use linear regression?

Answer 21

If your DEPENDENT variable increases or decreases linearly with your INDEPENDENT variable

Question 22

What to do if your dependent variable doesn’t vary linearly with your independent variable

Answer 22

Transform the data or do non-linear regression

Question 23

Is the Chi squared test parametric?

Answer 23

No, so it does not make assumptions about normality or equal variances

Question 24

What is the Chi squared test used for?

Answer 24

Used for looking at counts of discrete events

Question 25

What does the Chi squared test require?

Answer 25

That all counts are independent

Question 26

What are the two ways to use the Chi squared test?

Answer 26

1. Goodness of fit 2. Test of association The difference is the way we calculate the expected values with which to compare our observations

Question 27

Chi squared goodness of fit

Answer 27

Prior knowledge of what expected ratios will be (e.g. Mendelian inheritance has known ratios of offspring)

Question 28

Chi squared test of association

Answer 28

No fixed idea about the rations of expected results - instead they are calculated based on the assumption that there is no association between the two variables

Question 29

What is R Squared?

Answer 29

The proportion of variance measured which is due to the independent variable you are changing

Question 30

What is binary logistic regression?

Answer 30

Deals with cases where you measure a binary outcome such as dead vs. alive and you want to see if a predictor influences the proportions of your two possible outcomes

Question 31

What statistic do you look at for binary logistic regression?

Answer 31

Wald statistic

Question 32

What is the non-parametric version of a repeated-measures ANOVA? What is its shortcoming?

Answer 32

Friedman test | Can’t deal with between-subjects factors

Question 33

What is Poisson probability?

Answer 33

Used to calculate the probability of n occurrences of an event when you already have a measure of the average

Question 34

What is homoscedasticity?

Answer 34

Equal variance over a range of y-values

Question 35

Does binary logistic regression assume equal variances and normally distributed residuals?

Answer 35

No