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Q: When to t test z test t interval z interval etc?
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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 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.


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.


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 Z value for 90 percent confidence interval estimation?

The answer depends on whether the test is one-tailed or two-tailed.One-tailed: z = 1.28 Two-tailed: z = 1.64


What is the critical z value that corresponds to a confidence level of 88 percent?

z = 1.56 gives a 2-tailed interval for 88%.z = 1.56 gives a 2-tailed interval for 88%.z = 1.56 gives a 2-tailed interval for 88%.z = 1.56 gives a 2-tailed interval for 88%.


When finding a confidence interval for true mean spent of all citizens should you us a z-score or t-score?

If the sample size is less then 30 use the T table, if greater then 30 use the Z table.


What is the Z value for 91 percent confidence interval estimation?

The Z-value for a one-sided 91% confidence interval is 1.34


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.


Why would you use a z test rather than a t test?

When the sample size is greater than 30


Why would you use a t test rather than a z test?

When the sample size is greater than 30