Psychology 5510 H01Coding Schemes
For each problem,
A) conduct the appropriate analysis and
B) write a 1 page description of the results.
C) submitthe Summary Table, ANOVA table, and Coefficients Table.
Remember neatness and clarity counts.
1. (From Howell, 4th Ed. p. 320). EFFECTS OF THC ON ACTIVITY IN RATS
The following example illustrates the calculation of a one-way analysis of variance with unequal sample sizes. At the same time, it provides a second example of many of the ideas already presented.
The nucleus accumbens is a forebrain structure that has been shown to be involved in locomotor activity in rats. Systemic administration of low doses of tetrahydrocannabinol (THC, the major active ingredient in marijuana) is known to increase locomotor activity, whereas high doses 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 (J.Lg) of THC into the nucleus accumbens of rats. The investigators recorded the activity level of animals before and after the injection. Activity was recorded by placing the animal in a test chamber and suspending the chamber on rubber mounts. The vibrations of the chamber as the animal moved around were transduced by an accelerometer and converted to activity units, which were read off a meter. These units, then, were arbitrary, a point that will become relevant when we consider transformations. Conti and Musty took as their dependent variable the rat's activity for 10 minutes after the injection as a proportion of the rat's activity in the 10 minutes before the injection. Since animals generally decrease their activity as they become accustomed to an apparatus, ratios were expected to be less than 1. However, it was anticipated that those rats with intermediate levels of THC would decrease their activity less (exhibit a higher postinjection/preinjection ratio) than would those with either low or high levels. (Intermediate levels were expected to lead to the greatest activity, because very low doses should be insufficient to produce an effect and high doses should lead to decreases in activity.)
The data for this study are presented in Table 11.4a. The decimal points have been omitted from the proportions for ease of calculation, but this will have no effect on the results-all sums of squares will be affected equally and the resulting F value will be the same as it would be if the decimals were used. Table 11.4b shows boxplots for the individual groups. Although there are too few data points to say much about the shape of the distributions, it would appear that there is a slight negative skewness in all the groups, as judged by the location of the median within the box. The fact that the skewness is in the same direction for all groups and that it is not serious suggests that we can go ahead and run an analysis of variance.
The data, in copyable form are as follows . . .
P595F9H02 - 1 10/28/18
1 30
1 27
1 52
1 38
1 20
1 26
1 8
1 41
1 49
1 49
2 60
2 42
2 48
2 52
2 28
2 93
2 32
2 46
2 63
2 44
3 71
3 50
3 38
3 59
3 65
3 58
3 74
3 67
3 61
4 33
4 78
4 71
4 58
4 35
4 35
4 46
4 32
5 36
5 27
5 60
5 51
5 29
5 34
5 24
5 17
5 50
5 53
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Analyze the data using the appropriate coding scheme. As part of the analysis, you should be able to compare each drug group with the control group.
2. A psychologist was studying the effects of type of presentation style responses to political messages. Five groups of persons were shown different videos of a speech with essentially the same message. But the styles of presentation of that message were manipulated.
Group 1 received the message using all possible techniques designed to discourage participants from accepting the message.
Group 2 received the message, this time with just a few techniques designed to discourage acceptance of the message.
Group 3 received the message in a video with no special techniques for acceptance or nonacceptance of the message.
Group 4 received the message created with a few techniques designed to encourage acceptance of the message.
Group 5 received the message delivered with all possible techniques designed to encourage acceptance of the message.
The researchers want to determine which groups had the most extreme acceptance or nonacceptance of the message and whether any group was significantly more accepting or nonaccepting than the total sample mean across all five groups.
Use the appropriate group coding scheme to determine which groups were most extreme, i.e., had the largest deviation from the overall mean, and whether the extremity was significant or not.
The data for this part are below. They’re also on my web site as “group coding assignment.”
The data are as follows.
P595F9H02 - 1 10/28/18
id group rating
1 1 39
2 1 48
3 1 45
4 1 44
5 1 29
6 1 30
7 1 45
8 1 64
9 1 46
10 1 45
11 1 45
12 1 36
13 1 62
14 1 39
15 1 44
16 1 30
17 1 33
18 1 58
19 1 55
20 1 54
21 1 48
22 1 39
23 1 63
24 1 45
25 1 48
26 1 62
27 1 46
28 1 45
29 1 55
30 1 38
31 1 48
32 1 59
33 1 34
34 1 45
35 1 40
36 1 45
37 1 37
38 1 59
39 1 62
40 1 36
41 2 49
42 2 53
43 2 49
44 2 53
45 2 50
46 2 46
47 2 57
48 2 50
49 2 50
50 2 52
51 2 37
52 2 25
53 2 57
54 2 60
55 2 53
56 2 39
57 2 44
58 2 72
59 2 42
60 2 44
61 2 60
62 2 59
63 2 38
64 2 67
65 2 54
66 2 42
67 2 48
68 2 60
69 2 59
70 2 28
71 2 66
72 2 45
73 2 54
74 2 48
75 2 35
76 2 58
77 2 44
78 2 40
79 2 29
80 2 57
81 3 46
82 3 42
83 3 41
84 3 30
85 3 45
86 3 30
87 3 33
88 3 54
89 3 57
90 3 44
91 3 54
92 3 67
93 3 51
94 3 57
95 3 37
96 3 40
97 3 40
98 3 48
99 3 53
100 3 37
101 3 67
102 3 43
103 3 37
104 3 54
105 3 52
106 3 40
107 3 61
108 3 48
109 3 44
110 3 65
111 3 57
112 3 50
113 3 58
114 3 65
115 3 48
116 3 34
117 3 44
118 3 58
119 3 45
120 3 35
121 4 46
122 4 53
123 4 38
124 4 46
125 4 55
126 4 49
127 4 54
128 4 56
129 4 25
130 4 47
131 4 53
132 4 52
133 4 60
134 4 35
135 4 49
136 4 54
137 4 55
138 4 65
139 4 39
140 4 57
141 4 53
142 4 51
143 4 66
144 4 50
145 4 46
146 4 36
147 4 54
148 4 20
149 4 55
150 4 56
151 4 57
152 4 43
153 4 49
154 4 39
155 4 38
156 4 33
157 4 43
158 4 46
159 4 52
160 4 58
161 5 62
162 5 47
163 5 40
164 5 60
165 5 62
166 5 37
167 5 59
168 5 51
169 5 49
170 5 55
171 5 66
172 5 38
173 5 66
174 5 64
175 5 72
176 5 58
177 5 47
178 5 62
179 5 76
180 5 33
181 5 58
182 5 40
183 5 44
184 5 52
185 5 53
186 5 49
187 5 39
188 5 46
189 5 64
190 5 53
191 5 74
192 5 48
193 5 41
194 5 44
195 5 62
196 5 67
197 5 53
198 5 45
199 5 59
200 5 48
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