Statistics
One-Variable & two-variable data
AP Statistics
Unit 9: Inference for Quantitative Data: Slopes
Chi-Square
Goodness of Fit
Test for Independence
Test for Homogeneity
Significance Test
P-value
Categorical Variables
Regression Line
T-test for Slope
Degrees of Freedom
Null Hypothesis
Alternative Hypothesis
tCDF
10th
What does a low chi-square indicate?
The sample meets expectations.
What does a high chi-square indicate?
The sample does not meet expectations.
How do you find the p-value GIVEN the chi-square value?
You plug in the chi-square value as the lower boundary and, depending on your hypothesis, double it.
How do you know when to test for homogeneity?
When there are at least two samples and one variable is recorded.
How do you know when to test for independence?
When there is one sample with two/multiple variables being recorded.
What does chi-square measure?
How much the observed counts deviate from the expected counts.
What happens if you have a large chi-square value? Is this evidence against the HO?
Yes
How do you calculate the degrees of freedom for two-way tables?
You do number of columns-1 times the number of rows-1
How do you write a null hypothesis for Chi-Square test for Homogeneity?
There is no difference in the distribution of _____ for several populations/treatments
How do you write a null hypothesis for a Chi-Square test for Independence?
Ho: There is no association between (categorical 1) and (categorical variable 2)
What does independent mean?
no association
How do you find expected counts for two way tables?
(Row Total * Column Total)/Table Total
DO THIS FOR THE SMALLEST VALUES
How do you know when to use chi-square versus T-test/z-tests?
Because chi-square is for categorical variables while T and Z are for quantitative.
What do you have to say in the Plan step?
You need to say your test type “EX: chi-square goodness of fit, chi-square test for independence”
What is the general equation for a population regression line?
UY = a+Bx
How do you calculate the degrees of freedom for t-interval for slope?
df=n-2
When you’re doing a t-test for slope, what is your Null hypothesis?
Ho: B = Bo
True slope = Claimed Slope
How do you find the p-value given the test statistic in a t-test for slope?
tCDF where df is n-2
What is the USUALLY the alternate hypothesis in t-test for slope?
HA: B≠0
What is the calculator test for t-test for slope called?
Linear Regression t-test.
How do you calculate the degrees of freedom for a chi-square goodness of fit test?
df = n-1
What is the null/alternative hypothesis for a chi-square goodness of fit test?
HO: The stated distribution of _______ is correct
HA: The stated distribution is not correct