Lecture 6 Flashcards
What is a t-test?
Testing the difference of 2 means
What is a one-sample t-test?
Is the mean of a given sample significantly different from a pre-selected value?
What is an independent samples t-test?
Are the means of 2 independent groups significantly different from one another?
What is a paired samples t-test?
Do the means of the same individuals, given 2 different conditions/treatments/ levels of the IV show a difference between conditions? Groups are not independent.
What is the equation to perform a t-test?
t= mean of sample-expected value/estimate of standard error
What is standard error?
The sample might not perfectly represent the entire population-we get sampling variation- means of different populations vary to some extent. Tells us how spread out or clustered the sample means are
What is a sampling distrubution?
Frequency distribution of all samples of means from that population-tends to be normally distributed.
What is the standard deviation of the sampling distribution?
Standard Error
What does the mean of the sampling distribution equal?
The population mean
What does standard deviation tell us?
How representative the mean is of the entire population
How do you calculate standared error?
Standard deviation/ Square root of population size
What is the central limit theorum?
If the sample is large enough, it will be representative of the population. Larger samples make the distribution narrower and SD becomes smaller. Keeps the same mean
What is the minimum sample size you can have so you can make sure it is representative?
25-30
What does SEM show us?
How extreme a value can be plausible given sampling variation-if the score is greater or less than what would be plausible based on SEM, then it is said to be significantly different.
What can you not do with independent samples?
Random assignment-pre existing information determines the groups (quasi-exerpiment
