I’m working on a statistics multi-part question and need guidance to help me learn.

In Ch. 9 we learned to conduct a t test to compare the mean of a sample to the mean of its population when we know the population’s mean, but we don’t know its SD. The term for this kind of t test is single sample t test or one sample t test, because it uses data from only one sample.

Example of a single sample t test

First, as an example of how to conduct a single sample t test, we’ll use the data from Examples 9.2, 9.3, and 9.5. You can see the raw data in Figure 9.5 (p. 305). These data are in the Example_9-2.csv file.

(1) Download Example_9-2.csv and open it in Jamovi.

(2) Make sure the Measure type and Data type are correct.

(3) From the Analyses tab, select T-Tests and One Sample T-Test.

(4) Move the alertness scores into the Dependent Variables box.

(5) From the Tests menu select Student’s.

(6) From the Hypothesis menu enter 50 in the Test value box and select ? Test value. This tells Jamovi that the population mean specified by the null hypothesis is 50. This is the test value that we’ll test the sample mean against. We’re also telling Jamovi that the alternative hypothesis is that the unknown mean of the treated population is NOT equal to the test value of 50. This is a non-directional hypothesis.

(7) From the Additional Statistics menu select Mean difference and enter 95 for Confidence interval. Also check Effect size and Descriptives.

(8) Save your analysis as Example_9-2.omv, to be submitted as part of this assignment.

If you did everything right, you should see that your results match those reported in the textbook for sample mean, df, estimated standard error, t, p, and estimated Cohen’s d.

As for the confidence interval (CI), notice that Jamovi calculates the CI around the mean difference. This is different from the textbook where we learned to calculate the CI around the sample mean. We can easily convert the CI around the mean difference to CI around the sample mean by adding the lower bound and the upper bound to the test value of 50, keeping in mind that if one of these values is a negative number, that means we should subtract it from the test valueof 50. The resulting values will be the lower and upper bounds of the CI around the mean, and you should see that they match those for the 95% CI reported for these data in Example 9.5.

Low-birthweight infants

Low-birthweight (LBW) infants are a problem for their parents because they are less responsive and predictable than normal birthweight infants as well as being at risk for physical and developmental problems. Nurcombe et al (1984) reported on a program designed to make mothers more aware of infants’ signals and more responsive to their needs. One of the dependent variables in the study was the Psychomotor Development Index (PDI) of the Bayley Scales of Infant Development. Higher PDI scores are better than lower PDI scores. The file, LBW.sav, attached to this assignment, contains the six-month PDI scores for the 56 infants in the study. We will use these data to illustrate the one-sample t test by comparing the mean PDI score of these infants to the normative population mean of 100.

(1) Download LBW.sav, open it in Jamovi, and conduct a single sample t test. All settings should be the same as for the Example_9-2 except for one: For Test value enter 100.

(2) Save the Jamovi file as Ch09_YourLastName.omv and use it to answer the questions on the worksheet.

Instructions for submitting this assignment.

(1) Locate Example_9-2.omv, Ch09_YourLastName.omv, and Ch09 Homework.docx where you saved them on your computer.

(2) Click the title of this assignment ( Ch09 Homework) to open the Upload Assignment page.

(3) In the ASSIGNMENT SUBMISSION section, attach Example_9-2.omv, Ch09_YourLastName.omv, and the Ch09 Homework file. Click Submit.

(4) If you submit this assignment early enough, I might have time to provide feedback that you can use to improve it and possibly improve your grade. So soon after you submit it, return to this assignment to see if I’ve given you any feedback. Click the assignment title and on the Review Submission History page you’ll see the details of your prior submissions. To revise a prior submission, click Start New, download and revise, be sure to save it, and upload it as previously.