Sampling & Experiments
Every member of the population has an equal chance of being selected.
Simple Random Sample
Probability of rolling a 6 on a fair die.
1/6
Increasing sample size does what to margin of error?
decreases it
The null hypothesis is usually written as what symbol?
H₀
What does a positive slope indicate?
Positive Association
Assigning subjects to treatments by chance is called what?
Random assignment
If P(A)=0.4 and P(B)=0.5 and independent, find P(A and B).
0.20
A 95% confidence interval captures the true parameter about what percent of the time?
95%
If p-value < α, what decision is made?
Reject H₀
The correlation coefficient is represented by what letter?
r
An experiment with two treatments where each subject receives both treatments.
(Matched pairs design)
What probability distribution models number of successes in n trials?
Binomial
Larger confidence level means a wider or narrower interval?
WIder
Rejecting a true null hypothesis is what type of error?
Type I error
Correlation measures the strength and direction of what type of relationship?
Linear
A lurking variable that affects both explanatory and response variables.
(Confounding variable)
Probability of at least one success = 1 minus what?
(Probability of no successes)
What critical value is commonly used for a 95% z-interval?
1.96
A p-value represents what probability?
(Probability of getting results at least as extreme assuming H₀ is true)
What does r² represent?
Percent of variation explained by the regression model
Dividing a population into groups and randomly selecting individuals from each group.
(Stratified random sample)
Mean of a binomial distribution.
np
If the sample size quadruples, margin of error changes by what factor?
cut in half
Failing to reject a false null hypothesis is what type of error?
Type II error
In a residual plot, a random scatter suggests what?
A linear model is appropriate