Test #1 Flashcards
How do you calculate variance?
Mean of the squared dev from the population mean
How do you calculate SD?
Square root of the variance
In a histogram the y value is the
frequency of the observation
if the mean is greater than the median the data is skewed _____
right
if the mean is less than the median the data is skewed ____
left
In a histogram the x value is the
numerical value
What is the P-Value
It is the margin of error; how likely it is that your data could have ocurred under null hypothesis
When should I reject the null?
P < α
What is a type 1 error?
Reject the null hypthesis even though the null is true (false positive)
What is a type 2 error?
Fail to reject null hypothesis even though null is false (false negative)
If P value is > α then
fail to reject null
if p value is < α then
reject null
How to calculate effect size?
(m1-m2)/ pooled SD
When is non-parametric test used?
is is used for samples not normally distributed; usually sample size is small
What is more powerful, non-parametric or parametic test?
Parametric tests are more powerful but more dangerous
