A psychologist decided to study whether rocking babies in a mechanical baby rocker would affect weight gain. To test this, 8 premature babies at a local hospital were selected to participate in the experiment. The babies were rocked for 10 minutes a day for a week and then weighed. Then the same babies were rocked for 30 minutes a day for a week and then weighed. The change in their weight across the week was measured in ounces. The data and analyses of the t-test, are given below.
A psychologist decided to study whether rocking babies in a mechanical baby rocker would affect weight gain. To test this, 8 premature babies at a local hospital were selected to participate in the experiment. The babies were rocked for 10 minutes a day for a week and then weighed. Then the same babies were rocked for 30 minutes a day for a week and then weighed. The change in their weight across the week was measured in ounces. The data and analyses of the t-test, are given below.
Note that the difference scores are analyzed as 30-Min minus 10-Min.
Baby Rocked 30 Min Rocked 10 Min D = 30 – 10 D2
1 27.6 29.7 -2.1 4.41
2 25.4 28.5 -3.1 9.61
3 30.5 39.8 -9.3 86.49
4 33.8 38.8 -5.0 25
5 24.5 25.0 -0.5 .25
6 16.4 22.6 -6.2 38.44
7 19.8 24.7 -4.9 24.01
8 23.8 26.9 -3.1 9.61
Σ D = -34.2 Σ D2 = 197.82
D-bar = -4.275
What is the observed value of the test statistic?
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