SPSS ANOVA Assignment

STAT310

Fall 2020

You will find the data for this assignment on Blackboard.

Assume independence, normality and equal variances.

1.An example of a one-way analysis of variance will illustrate the treatment of unequal sample sizes. In a study of the development of low-birth-weight (LBW) infants (Nurcombe et al., 1984), three groups of newborn infants differed in terms of birth weight and whether their mothers had participated in a training program about the special needs of low-birth-weight infants. The mothers were then interviewed when the infants were six months old. There were three groups in the experimentan LBW-Experimental group, an LBW-Control group, and a Full-Term-Control group. The two control groups received no special training, and so serve as reference points against which to compare the performance of the trained (experimental) group. The LBW-Experimental group received the intervention program, and we hoped to show that those mothers would adapt well to their new role as well as mothers of full-term infants. On the other hand, we expected that mothers of low-birth-weight infants who did not receive the intervention program would have some trouble adapting. (Being a parent of a low-birth-weight baby is not an easy task, especially for the first few months.)

Use the data set Birth_Data, which contains the dependent variable: the score on a maternal adaptation scale. A higher score indicates poorer adaptation.

Group 1 LBW-Experimental

Group 2 LBW-Control

Group 3 Full-Term

Using the ANOVA process, with Tukey's pairwise comparisons, answer the following two questions:

a.. Are there differences between the mean of mothers in the LBW-Control group and the mean of mothers in the Full-Term group? If you find a difference, explain the difference.

b.. Are there differences between the mean of mothers in the LBW-Control group and the mean of mothers in the LBW-Experimental group? ANOVA analysis follows.

2.What does marijuana do, and how does it do it? Aside from its better-known effects, marijuana increases, or in some cases decreases, locomotor (walking around) behavior. The nucleus accumbens is a forebrain structure that has been shown to be involved in locomotor activity in rats. (It is also thought to control feelings of pleasure.) Administration of low doses of tetrahydrocannabinol (THC, the major active ingredient in marijuana) is known to increase locomotor activity, whereas high doses are known to lead to a decrease in activity. In an attempt to examine whether THC is acting within the nucleus accumbens to produce its effects on activity, Conti and Musty (1984) bilaterally injected either a placebo or 0.1, 0.5, 1, or 2 micrograms (mg) of THC directly into the nucleus accumbens of rats. The investigators recorded the change in the activity level of the animals after injection. It was expected that activity would increase more with smaller injections than with larger ones.

The data in file marijuana.mpj represent the amount of change (decrease) in each animal.

First set up the null hypothesis, which states that all of the samples were drawn from populations with the same mean. In other words, H0: m1 = m2 = m3 = m4 = m5.

For consistency we will test this null hypothesis with a significance level of = .05.

Use the Fisher or Tukey pair-wise comparisons to determine the differences, if any, between the groups.

3.What effect does smoking have on performance? Spilich, June, and Renner (1992) asked nonsmokers (NS), smokers who had delayed smoking for three hours (DS), and smokers who were actively smoking (AS) to perform a pattern recognition task in which they had to locate a target on a screen. The dependent variable was latency (in seconds). The data are presented below. Plot the resulting means and run the analysis of variance. On the basis of these data is there support for the hypothesis that smoking has an effect on performance?

You will find all the data on the author's website: https://www.uvm.edu/~dhowell/fundamentals8/DataFiles/DataSets.html

Data is also in Blackboard file Smokers contains the data for this exercise.

Use either the Fisher or Tukey pair-wise comparisons to determine the difference between the groups, if there are any.