Researchers were interested in the effects co-sleeping on night-time waking and crying in infants. They assessed the number of minutes parents reported that their infants were awake and crying for a period of 3 days. Ten of the infants co-slept with their mothers (Co) and 10 infants slept in a crib in another room (Cr). The infants were matched in pairs based on their age in days at the start of the study and based on the status of being breastfed or bottle fed since these two variables are known to affect rates of night-waking and crying. The researchers wanted to see if their was a difference in the total number of minutes of crying during the 3 nights for the 2 groups of infants. What type of test should they use to test this hypothesis? A z-test, a single sample t-test, a dependent samples t-test, or an independent samples t-test?
a dependent samples t-test
(since sample subjects in both groups are paired on the basis of age in days at the start of the study and based on the status of being breastfed or bottle fed
Researchers were interested in the effects co-sleeping on night-time waking and crying in infants. They assessed...
Researchers were interested in the effects of maternal stress on infants' production of stress hormones. They measures the level of the hormone "cortisol" in infant saliva when all the infants were 9 months old. The mothers were categorized according to the amount and type of stress they experienced while pregnant. One group of mothers reported no extraordinary stressors while pregnant. One group of mothers were living in the New York City area when the terrorist attack on the twin towers...
1. We reject the null hypothesis only when: a. our sample mean is larger than the population mean. b. the p value associated with our test statistic is greater than the significance level of the test we have chosen. c. our sample mean is smaller than the population mean. d. the p value associated with our test statistic is smaller than the significance level of the test we have chosen. 2. In a study of simulated juror decision making, researchers...