Question

A. For each study identify: IV, DV and the number of samples used. B. Think about the differences among the studies and suggest the ap! unterences among the studies and suggest the appropriate statistical test (use Study guide 2 for possible tests) C. Perform the test for study # 1 and study #3. 1. A researcher knows that the weights of 6-year old children are normally distributed with 20.9kg and 0 - 3.2. She suspects that children in poverty-stricken regions are undernourished and therefore underweight with a sample of n = 16 children, the researcher obtains a sample mean of M = 18.3. Use a one-tailed test and the 01 of significance to determine if the weights for this sample are significantly lower than what would be expected for the regular population of 6-year-old children. 10 2. A researcher is testing the effect of a new cold and flu medication on reaction time. A sample of n students is obtained and each student is given the normal dose of the medicine. Thirty minutes later, each student's reaction time is measured. The scores for the sample averaged 3. A biopsychologist studies the role of the brain chemical serotonin in aggression. One sample of rats serves as a control group and receives a placebo. A second sample of rats receives a drug that lowers brain levels of serotonin. Then the researcher tests the animals by recording the number of aggressive responses each of the rats display. The data are presented below. Does the drug have a significant effect on aggression? Use an alpha level of .05, two tails. Low Serotonin n= 6 M = 22 SS = 108 Control n = 8 M = 14 SS = 180

Answer 1

1) Independent variable : Poverty stricken region

Dependent Variable : Weight of the children

number of samples used 16

NULL HYPOTHESIS H0:

u= 20.9kg

ALTERNATIVE HYPOTHESIS Ha:

μ< 20.9kg

alpha=0.01

Since Population standard deviation is known therefore Z test will be used.

Z= 18.3-20.9/3.2/sqrt(16)

Z= -2.6/3.2/4

Z= -2.6/0.8

Z= -3.25

The P-Value is .000577. The result is significant because p < .01.

Decision: REJECT NULL HYPOTHESIS H0

Conclusion: We have sufficient evidence to conclude that the weight for this sample is significantly lower than 20.3 kg

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