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may need turn all plots off. Not all plot types are compatible. These instructions assume that the population standard deviation is unknown. To do the procedures when s is known, use the corresponding ZTest or ZInterval. The only difference is that there is a space for you to input the value of s. In practice, we rarely know the
population standard deviation.
To make a confidence interval for a population mean (S unknown):
1. Press K and scroll to the TESTS menu.
2. Scroll down to the option TInterval and select it.
3. If you have the sample data in a list, select the Data option and enter the list name with the data. See
the top screen to the right.
4. If you have only the summary statistics, choose the Stats option and enter the summary statistics
(sample mean and standard deviation, and sample size). See the second screen to the right.
5. Determine your conﬁdence level, and select Calculate. Press [. The output screen shows the
conﬁdence interval in a set of parentheses and calculates and reports the sample’s summary statistics.
To conduct a hypothesis test for a population mean (S unknown):
1. Write down your null and alternative hypotheses.
2. Press K and scroll to the TESTS menu.
3. Scroll down until you ﬁnd the option TTest and select it.
4. If you have the data, select the Data option and enter the list name with the data. See the screen to
the right.
5. If you have only the summary statistics, choose the Stats option and enter the summary statistics
(sample mean and standard deviation and sample size).
6. Each process will also require you to input the value of the population mean speciﬁed in your null hypothesis— the m0 . 5. If you have only the summary statistics, choose the Stats option and enter the summary statistics (sample mean and standard
deviation, and sample size) for each of your samples. 6. The line beginning with m1 allows you to select the form of the alternative hypothesis— use the arrow keys to move the cursor left
and right to select the correct form of your alternative hypothesis. Press [ to select it.
If you are using the pooled procedures, choose Yes; otherwise, select No. You may have to scroll down to see this line.
Select Calculate and press [. The output screen repeats the form of the alternative hypothesis selected. The test statistic, t,
and the pvalue, p, are reported. The degrees of freedom for the test and the summary statistics are also displayed. Inferences for the Difference between Two Proportions 7. Note: If you get an error message, see the warning above for oneproportion procedures.
To make a confidence interval for the difference between two proportions:
1. Press K and scroll to the TESTS menu.
2. Scroll down until you ﬁnd the option 2 –PropZInt and select it.
3. Enter the number of successes (x1) and sample size (n1) for the ﬁrst sample.
(Again number, not proportion, of successes.)
4. Enter the number of successes (x2) and sample size (n2) for the second sample.
5. Determine...
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 Spring '14
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