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How do I know what type of t-test to use?
If you are studying one group, use a paired t-test to compare the group mean over time or after an intervention, or use a one-sample t-test to compare the group mean to a standard value. If you are studying two groups, use a two-sample t-test. If you want to know only whether a difference exists, use a two-tailed test.
How do you know when to use a one sample t test?
The one sample t test compares the mean of your sample data to a known value. For example, you might want to know how your sample mean compares to the population mean. You should run a one sample t test when you don’t know the population standard deviation or you have a small sample size.
Does t-test compare means?
Essentially, a t-test allows us to compare the average values of the two data sets and determine if they came from the same population. Mathematically, the t-test takes a sample from each of the two sets and establishes the problem statement by assuming a null hypothesis that the two means are equal.
When do you use a paired t test?
Onlyif there is a direct relationship between each specific data point in the first set and one and only one specific data point in the second set, such as measurements on the same subject ‘before and after,’ then the paired t testMAY be appropriate.
When to use the Student’s t test?
‘Student’s’ t Test (For Independent Samples) Use this test to compare two small sets of quantitative data when samples are collected independently of one another. When one randomly takes replicate measurements from a population he/she is collecting an independent sample.
What is the statistic for two sample t test?
The two sample t test yields a statistic t, in which X-bar, of course, is the sample mean, and s is the sample standard deviation. Note that the numerator of the formula is the difference between means. The denominator is a measurement of experimental error in the two groups combined.
Can a t test be performed without raw data?
The t test can be performed knowing just the means, standard deviation, and number of data points. Note that the raw data must be used for the t test or any statistical test, for that matter. If you record only means in your notebook, you lose a great deal of information and usually render your work invalid.