(a) Scientists have used Mongolian gerbils when conducting neurological research
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Question
(a) Scientists have used Mongolian gerbils when conducting neurological research. A certain breed of these gerbils was crossed and gave progeny of the following colors:
Is this data consistent with the 1:2:1 ratio predicted by a certain genetic model? Use a chi-square test at = 0.05.
(b) Suppose that scientists suspected that brown gerbils were more likely to produce progeny with birth defects than black progeny. The progeny of the black and brown gerbils in the previous part were all assessed for birth defects. The results were as follows:
Based on this table, conduct a hypothesis test to assess whether a gerbil having progeny with birth defects is independent of being black or brown. Use = 0.01.
Color Black Brown White Number of Progeny 40 59 42Explanation / Answer
a) applying chi square goodness of fit on above data:
for above 2 degree of frreedom and 0.05 ;level ; critical value =5.991
as test stat 3.8085 is less then critical valuie we can not reject null hypothesis.
hence data is consistent with the 1:2:1 ratio predicted by a certain genetic model
b)
applying chi square test of independence on above data:
for above 1 degree of freedom and 0.01 level ; critical value =6.635
as test stat 13.689 is higher then critical value we reject null hypothesis and conclude that having progeny with birth defects is dependent of being black or brown
observed Expected Chi square Type Probability O E=total*p =(O-E)^2/E black 0.250 40.000 35.25 0.64 brown 0.500 59.000 70.50 1.88 white 0.250 42.000 35.25 1.29 1 141 141 3.8085Related Questions
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