Chapter 9- Single Sample T test Flashcards
What is the t distribution?
The t distribution allows us to compare two groups
Name the 3 t distributions
The 3 t distributions are: single sample t test, the paired sample t test, and the independent t test
When does a researcher use the t distribution?
The researcher uses the t distribution when they wan to compare to samples and the population standard deviation is unknown
Name the 2 distributions and are they observed or theoretical?
Population (theoretical-M cursive, standard deviation is a small o), Sample Distribution (Observed- X bar, standard deviation is SD), and Sampling (theoretical- double M cursive and regular, standard deviation is standard error)
What is a single sample t test?
A single sample t-test is when you compare data from one sample to a population where we know the mean but not the standard deviation.
What does the t statistic tell us?
The t statistic tells us the distance of a sample mean from a population mean in terms of standard error
What correction is made to the t statistic formula when calculating the standard error? What does this correction do?
Reduce the denominator (N) by subtracting 1. Dividing by a slightly smaller number increases the value of the standard deviation. This is done because there is some level of error when estimating the population SD
After the correction is made, why does a researcher need to make his spread of the distribution of means smaller?
The spread of the distribution of means needs to be made smaller to reflect the fact that the distribution of means is less variable than a distribution of scores
What is the degrees of freedom?
The degrees of freedom is the number of scores that are free to vary when estimating a population parameter from a sample
When does the t distribution come close to the z distribution?
The t distribution becomes close to the z distribution as the sample sizes increase
Name the 6 steps of the Single Sample t test?
1) Identify pops, dibs, and assumps 2) State the null/research hypothesis 3) Determine the characteristics of the comparison dibs 4) Determine the critical values or cut offs 5) calculate the test statistic 6) make a decision
What test is run for effect size for the single sample t test?
For effect size, Cohen’s d is run for the single sample t test
What is a paired sample t test?
A paired sample t test is used to compare two means for a within groups design (every participant is in both samples)
A single sample t test is used to analyze a single sample of scores; a paired sample t test is used to analyze what?
For the paired sample test, the difference score is analyzed. The paired sample t test is a distribution of mean difference scores
When is a paired samples t test used?
A paired samples t test is when researchers have data for all participants under two conditions ( a within groups design)
