Biostats review

Question 1

What does an alpha value of 5% mean?

Answer 1

We are willing to conclude that a result is significant even if we have a 5% chance of being wrong

Question 2

Why do we use ANOVA when we have more than 2 independent variables?

Answer 2

The more t-tests we do, the greater the risk we take that one of those tests will be due to chance

Question 3

Define descriptive vs inferential statistics

Answer 3

Descriptive: analyses that help summarize our data
Inferential: allow us to make conclusions about relationships, or to generalize our sample’s findings to the population

Question 4

What is the point estimate? What is confidence interval?

Answer 4

Point estimate: the value calculated as the outcome

Confidence interval: used to describe the uncertainty around this estimate

Question 5

What 3 factors influence the size of the confidence interval?

Answer 5

1. Size of the CI calculated
2. Variability around the point estimate
3. Sample size

Question 6

What 3 factors influence the p value?

Answer 6

1. Effect size (larger the effect, less likely it was caused by chance alone)
2. The variability around the point estimate observed in the sample
3. The sample size

Question 7

What is a Type I error?

Answer 7

Reject null when it’s true

Ex. Telling a man he’s pregnant

Question 8

What is the probability of a Type I error?

Answer 8

Alpha