Researchers want to assess the sucking behaviors of infants who are fed from spe
ID: 3173014 • Letter: R
Question
Researchers want to assess the sucking behaviors of infants who are fed from special cups are the same as for infants who are fed from bottles as soon as possible after birth. They select 25 cup-fed and 24 bottle-fed infants. After eight months of measurements, the scores are collected and represent the time (in minutes) the infants suck their thumbs during the observation. Use the “infant feeding practices” data set to test the following Ho is: The populations from which the two samples have been drawn are identical.
The assumptions are that the subjects are randomly and independently sampled, the dependent variable is continuous, and the measurement scale is at least ordinal (alpha =.05)
Write the alternative hypotheses and compute the Mann Whitney U test both using the formula (show your work) and using SPSS. Are the results similar?
From the SPSS output, identify the following:
P-value
Z value corrected for ties
Mean rank for attitudes scores
Write the results of the analysis.
Submit a copy of the SPSS output
Ranks
Eating_habits
N
Mean Rank
Sum of Ranks
Score
Cup-Fed
25
20.86
521.50
Bottle-Fed
24
29.31
703.50
Total
49
Test Statisticsa
Score
Mann-Whitney U
196.500
Wilcoxon W
521.500
Z
-2.071
Asymp. Sig. (2-tailed)
.038
a. Grouping Variable: Eating_habits
Eat Score Rank
1 8 2.00
1 10 3.00
1 11 4.50
1 11 4.50
1 12 6.00
1 18 7.00
1 21 8.00
1 29 11.50
1 45 15.00
1 46 16.00
1 49 18.00
1 49 18.00
1 49 18.00
1 50 20.50
1 50 20.50
1 57 25.00
1 71 28.00
1 73 29.00
1 81 33.50
1 89 36.00
1 90 37.00
1 93 38.00
1 94 39.00
1 96 40.50
1 109 43.00
2 3 1.00
2 22 9.00
2 27 10.00
2 29 11.50
2 30 13.00
2 36 14.00
2 51 23.00
2 51 23.00
2 51 23.00
2 59 26.00
2 65 27.00
2 74 30.00
2 76 31.50
2 76 31.50
2 81 33.50
2 83 35.00
2 96 40.50
2 98 42.00
2 122 44.00
2 135 45.00
2 142 46.00
2 159 47.00
2 183 48.00
2 190 49.00
Ranks
Eating_habits
N
Mean Rank
Sum of Ranks
Score
Cup-Fed
25
20.86
521.50
Bottle-Fed
24
29.31
703.50
Total
49
Explanation / Answer
P-value=0.038
Z value for corrected for ties= -2.071
Mean ranks for attribute scores are = 20.86 (Cup-fed) and 29.31 (Bottle-fed)
Since the p-value is less than 0.05, the null hypothesis is rejected and it is concluded that the population from which the two samples are drawn are not same.
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