Chapter 9 Flashcards
Independent Samples
Two samples when the subjects selected for the 1st sample in no way influence the way the subjects are selected in the 2nd sample
Dependent Samples
Two samples where the selection of subjects for the 1st group in some way influenced the selection of subjects for the other group
Assumptions for the Z test to determine the difference between 2 means when pop. stand. deviation is known
- Both samples are random samples
- The samples are independent of each other
- Population standard deviation is known for both samples
2-SampZTest
Used when you have two pieces of information and the population standard deviation is known
Assumptions for 2 independent means when pop. stan. deviation is unknown
- Samples are random samples
- Sample data are independent of eachother
- Population standard deviation is unknown and sample size is at least 30
- If sample size is less than 30 populations must be normally or approx. normally distributed
2-SampTTest
Used when given 2 pieces of data and the population standard deviation is unknown
Pooled estimate of the variance
a weighted average of the variance using the 2 sample variances & the degrees of freedom of each variance as the weights
Dependent Samples
When subjects are paired or matched in some way
Sometimes called matched-pair samples
Assumptions for t-Test for 2 means when samples are dependent
- Sample/samples are random
- Sample data are dependent
- When sample size/sizes are less than 30, population/populations must be normally or approximately normally distributed
Assumptions for z-Test for 2 proportions
- Samples must be random samples
- Sample data are independent for one another
- Both samples np>/= to 5 & nq>/= to 5
2-Proportion z-Test
Used to find the difference between 2 propotions
