Which test to use when you have less than 30 sampling units? Amazon online interview question
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Answers ( 10 )
Student T-test
You can use t-test for a small sample (generally considered less than 30).
If your sample is ‘large enough (>30)’, then the distribution of the sample means or sampling distribution would follow a normal distribution, in which case you would use z-test.
A t-test would be necessary for small samples because their distributions are not normal.
t test
T test
T-test
We generally use t-test for a sample with size less than 30.
we use t-test , as for smaller samples we use t-test. (n<30)
and small samples does not follow normal distribution.
As variance depends upon sample size, more specifically on degree of freedom , and as the degree of freedom increases the sample distribution converges to follow normal distribution (Z-distribution).
t-test is used for less than 30 observations.
1) You can use the t-test for a small sample (generally considered less than 30)
2) We perform a One-Sample t-test when we want to compare a sample mean with the population mean
3) We perform a Two-Sample t-test when we want to compare the mean of two samples
4) If your sample is ‘large enough (>30)’, then the distribution of the sample means or sampling distribution would follow a normal distribution, in which case you would use z-test
The parametric test called t-test is useful for testing those samples whose size is less than 30. The reason behind this is that if the size of the sample is more than 30, then the distribution of the t-test and the normal distribution will not be distinguishable.