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Whereas a t-test is used for n30, where n=sample size. n < 30 or n > 30 is not entirely arbitrary; it is intended to indicate that n must be sufficiently large to use the normal distribution. In some cases, n must be greater than 50. Note, both the t-test and the z-test can only be used if the distribution from which the sample is being drawn is a normal distribution. A z-test can be used even if the distribution is not normal (but is not severely skewed) if n>30, in which case, we can safely assume that the distribution is normal.

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Q: What is the difference between t test and z test?
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What is the difference between t test and z test in hypothesis testing?

It depends on the population.Use t-test for a small population, N < 30; otherwiase, apply z-test or when N>=30.


What is the difference between 2 sample z test statistic and 2 sample t test statistic?

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Is T test similar to Z test?

no t test is similar to z test because t test ie used for unknown observation and z is for the medicne


Is there a qualitative difference between a Z train and a T train in China?

AnswerThe difference between Z train and T train is Z train normally won't stop between your station and the destination for more passengers. As to the comfort of seats, facilities and speed, they are almost the same.


What is the difference between Z-Test and The Z-score?

The Z-score is just the score. The Z-test uses the Z-score to compare to the critical value. That is then used to establish if the null hypothesis is refused.


Is there a statistical test to assess the difference between two ratios. I have numbers which are ratios and want to test whether there is a statistical difference between them?

You can use the z test for two proportions. The link below will do this test for you.


Is a z test or t test used more often?

t test, because the z test requires knowing the population standard deviation and that's rare. The t test embodies an estimate of the standard deviation.


What is a t-test?

a t test is used inplace of a z-test when the population standard deviation is unknown.


Difference between laplace transform and z transform?

the difference is the "S" and "Z" parameters. S used for analog computation while Z for digital processing. basically Z is the digital approximation of the analog frequency domain signal. Z=exp(sT) where T is the sampling time.


How do you decide whether to use a z test or a t test when testing a hypothesis about a population mean?

You use a z test when you are testing a hypothesis that is using proportions You use a t test when you are testing a hypothesis that is using means


What is the difference between z value and z score?

They refer to the same thing as do z-transformations.


How does the formula for the t test differ from the formula for the z test?

When we use a z-test, we know the population mean and standard deviation. When we use a t-test, we do not know the population standard deviation and thus must estimate this using the sample data that we have collected. If you look at your z-table and t-table, tcrit for df(infinity) = zcrit because at df(infinity) we would have an entire population and no longer need an estimate.