Type I and II Errors
What is a type I error?
A false positive; reject the null hypothesis when you shouldn't.
What kind of relationship is indicated by a correlation coefficient of 0.01? Give a strength and direction.
Weak, positive
A _____ variable takes a value of 0 or 1, and is added to a regression model to represent binary factors.
dummy variable
What is the null hypothesis?
The claim that no relationship exists between two sets of data or variables being analyzed.
The selection of a subset of individuals from within a statistical population to estimate characteristics of the whole population
What is a type II error?
A false negative; don't reject the null hypothesis when you should.
A proportional reduction in error (PRE) measure of association is a prediction-based metric that varies in magnitude between which two numbers?
e.g. Lambda, Somers' d, and Cramer's V
0 and 1
Write the regression equation when the y-intercept equals 12 and the slope is .8.
y = 12 + 0.8x
If your p-value is less than your significance level, alpha, what happens to the null hypothesis?
Reject the null hypothesis
As students enter the school in the morning, every 3rd child is asked about their favorite subject. What kind of sampling is this?
Systematic sampling
Alex takes a pregnancy test. What is the type I error that can be made?
Type 1: false positive: Alex thinks they are pregnant but really aren't
The Pearson correlation coefficient (r) varies in magnitude between which two numbers?
-1 and 1
regression coefficient
With a p-value of 0.06, what happens to the null hypothesis?
Fail to reject the null hypothesis
From each grade level, 20 high school students are randomly selected from each class to form a sample of 80 students. What kind of sampling is this?
Stratified sampling
Alex takes a pregnancy test. What is the type II error that can be made?
Type 2: false negative: Alex thinks they aren't pregnant when they are
Lambda measures the strength of a relationship between two ______ variables
Categorical variables
R-squared measures what?
The proportion of the variance for a dependent variable that's explained by an independent variable in a regression model
Explain in everyday language what a p-value of 0.04 means.
There is a 4% chance of observing the results you obtained if the null hypothesis is true.
Explain what random sampling is in everyday language.
Each sample has an equal probability of being chosen.
What's worse, Type I or Type II errors?
Type I
Ordinal-level variables
Define multicollinearity
Two or more independent variables have a high correlation with one another in a regression model, which makes it difficult to determine the individual effect of each independent variable on the dependent variable
What is the difference between one-tailed and two-tailed tests?
The one-tailed test refers to a test of the null hypothesis, in which the alternative hypothesis is articulated directionally. However, if the alternative hypothesis is not exhibited directionally, then it is known as the two-tailed test of the null hypothesis.
Sample size and sample standard deviation