Scenario + test examples

Question 1

Do people who receive a vaccine differ from those who do not in whether they get a disease in the next 5 years?

Answer 1

chi-squared contingency analysis

fisher’s exact test (if expected values aren’t large enough)

Question 2

Do people who finish college on average get a higher income than people who do not?

Answer 2

2-sample t-test - because we’re comparing the mean of income for those who finished college and those who didn’t

Question 3

How can we use the wing length of a bumble bee to predict its maximum flying speed?

Answer 3

linear regression

Question 4

Is the weight at age 2 different on average for sets of dogs that are fed one of 5 different kinds of dog foods?

Answer 4

one-way ANOVA

Question 5

How much variation in flying speed of bumblebees is predicted by their wing lengths?

Answer 5

r^2; coefficient of determination

Question 6

Does the number of yellow/wrinkled, yellow/smooth, green/wrinkled, and green/smooth peas in a cross fit the 9:3:3:1 ratio predicted by Mendel?

Answer 6

chi-squared goodness-of-fit

Question 7

Does the number of green and yellow peas from a cross fit the 3:1 ratio predicted by Mendel? (Imagine you have only 17 data points.)

Answer 7

binomial distribution

Question 8

Does the growth rate of sea stars vary with temperature? (with and without particular assumptions)

Answer 8

correlation (with assumptions)

spearman’s correlation (without assumptions)

Question 9

Does the relationship of sea star growth rate and temperature vary depending on whether calcium is added to the water or not?

Answer 9

ANCOVA

Question 10

Is the mean length of elephant trunks different in males and females?

Answer 10

2-sample t-test

Question 11

Are people equally likely to be born on each of the 7 days of the week?

Answer 11

chi-squared goodness-of-fit

Question 12

An experiment measured the effects of a treatment adding calcium to a diet, a treatment adding selenium to a diet, adding both, or neither, and measured the swimming speed of fish. Is there an effect on swimming speed of adding calcium, adding selenium, or an interaction between those two?

Answer 12

2-factor ANOVA

Question 13

Is tree height normally distributed?

Answer 13

Shapiro-Wilk test

Question 14

Do trees with and without added fertilizer have the same variance in growth rate?

Answer 14

Levene’s test

Question 15

Can we predict whether seed germinates or not from the weight of the seed?

Answer 15

logistic regression

Question 16

The developmental pathway leading to the formation of spots on butterfly wings has been studied by surgical excision of a small amount of tissue on the left wings of a set of butterflies, with the right wings left untouched. The size of the spots on these wings was subsequently measured. How would you test whether the manipulation had an effect on spot size?

Answer 16

paired t-test