Exam 2 Flashcards
(69 cards)
why would you used t instead of z?
z is a theoretical distribution
df
n-1
how do you add more uncertainty?
replace the funky o with an s in the SEM equation
what’s the other name for a t-distribution?
Student’s t-distributions
how are t and z-distributions different?
t has more area under the curve tp accommodate more uncertainty
how are t and z-distributions alike?
both have normal, bell-shaped curves
as df gets bigger how does that affect a t distribution?
looks more like a z distribution
how is a t table organized?
rows are df
columns are probabilities
single samples
no control group, one group of people, used to establish norms
paired samples
one group of people but use two different treatments
independent t-test
2 groups with different treatment but doesn’t assume equal variance
point estimator
difference between sample means (X1-X2)
what are the 2 ways to calculate degrees of freedom?
Welsh method and conservative method
f-test or Levene’s test
variance test to see if two samples are similar
what do you do if two samples are similar?
use an equation that uses a combined variance estimate (gives more degrees of freedom)
what do you do if two samples aren’t similar?
use less degrees of freedom
ANOVA
one-way analysis of variance
ANOVA definition
test group means for a significant difference
2 components of ANOVA
variance between groups and variance within groups
MBS
mean square between
MBS definition
quantifies the variance of group means around the group mean (variance between groups)
MSW
mean square within
MSW definition
quantifies the variability of data points in a group around its mean (estimate of the variance within groups)
f-statistic
ratio of the MSB and MSW
