A random sample of 20 items is selected from a population. When computing a conf

Question

A random sample of 20 items is selected from a population. When computing a confidence interval for the population mean when the population standard deviation is unknown, what number of degrees of freedom should be used to determine the appropriate t-value?

19

21

25

20

Suppose a researcher has a sample of nine and does not know the population standard deviation. In this case the researcher should:

Assume the sample standard deviation is the same as the population standard deviation

Test if the data is normal before using the t-statistic

Use the t-statistic and do not worry about the distribution of the underlying population.

d-Reduce the sample by 1 to adjust for degrees of freedom

When testing a null hypothesis against the alternative, the p-value tells us:

Whether the null is appropriately constructed

Whether the significance level should be changed

To reject the null if the p-value is less than the significance level

Whether the test is a one tailed or two-tailed test

19

21

25

20

Explanation / Answer

1) DF = N - 1 = 20 - 1 = 19 (Option A)

2)

Use the t-statistic and do not worry about the distribution of the underlying population.

3)

To reject the null if the p-value is less than the significance level

Use the t-statistic and do not worry about the distribution of the underlying population.

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