Correlation, Regression, Sample Size, & Power

Question 0

Correlation and regression

Answer 0

Advantages: maintain continuity of data, model one variable as a function of the other

Disadvantages: only measures linear relationship, only useful when both variables are continuous

Question 1

2 x 2 tables

Answer 1

Advantages: ease of interpretation, no distributional assumptions, can easily stratify by other variables, can calculate OR or RR

Disadvantages: if a variable is continuous requires arbitrary cutoff (loss of information)

Question 2

2-way scatter plots

Answer 2

The first step in analyzing association between 2 continuous variables X and Y

Question 3

Pearson correlation coefficient (r)

Answer 3

Determines whether two continuous variables (X and Y) are linearly related. Ranges between -1 (perfect negative correlation) and 1 (perfect positive correlation)

Question 4

R^2 coefficient of determination

Answer 4

R^2 is the proportion of the total variability in Y that can be explained by the linear association between Y and X

Question 5

Type I error

Answer 5

Incorrectly rejecting H0 when H0 is true; probability of type I error is also called significance level

Question 6

Type II error

Answer 6

Incorrectly failing to reject H0 when H1 is true

Question 7

Power

Answer 7

Power is the probability that we reject H0 when H1 is true