When does one use a t-test instead of a z-test
When σ is unknown
When is one-sample t-test used vs independent samples t-test
A one-sample t-test is used to compare a single group’s mean to a known or hypothesized population value, while an independent samples t-test is used to compare the means of two independent, separate groups
How does one calculate estimated standard error
z-test: σ/√n
t-test: s/√n
What does the estimated standard error measure
How much difference between M and μ is reasonable to expect
What are the steps of hypothesis for a t-tset
1: State the hypotheses and selec a value for α
2: Locate the critical region and use the t distribution table
3: Calculate the test statistic
4: Make a decision
How does the t distribution work
In large samples is similar to a z-distribution (normal distribution) and flatens out as one’s degrees of freedom decrease, when degrees of freedom is lowerone’s critical value becomes higher, and one has to move further from the mean to get beyond the threshold set by one’s alpha level
How does one calculate a one-sample t-statistic
t=M-μ/SM
How does one calculate degrees of freedom
n-1
How does one calculate Cohen’s D for a t-statistic
d=M-μ/σ
What does r² measure
Percentage of variance accounted for by the indepedent variable
How is r² interpreted
Between 0.01 and 0.08 (small effect), between 0.09 and 0.25 (medium effect), and between 0.25 and greater is a large effect
