4. The chi-square test for goodness of fit - No preference Aa Aa A developmental

Question

4. The chi-square test for goodness of fit - No preference Aa Aa A developmental psychologist is studying bonding between healthy newborn babies and immediate family members. He wants to know if one-week-old infants use smell to recognize their fathers. To investigate, he selects a random sample of one-week-old infants. Each infant is presented with a garment worn by his or her father and two garments worn by unrelated men. The psychologist observes which garment each of the infants orients toward The resulting data are summarized in the following table that shows the number of infants who oriented toward each of the three garments Actual Unrelated Unrelated Father Man #1 Man #2 15 19 The developmental psychologist wants to know if one-week-old infants orient toward the garment of their own father more often than might occur by chance. He plans to use a chi-square test for goodness of fit to test his hypothesis The null hypothesis, that the one-week-old infants have no preference for the different garments, can be represented by the following, where the values specify the proportion of the population of one-week-old infants who would orient toward each of the garments Actual Father Unrelated Unrelated Man #1 Man #2

Explanation / Answer

Ans:

Test statistic:

Chi square scoe=4.290

df=3-1=2

critical chi square=CHIINV(0.05,2)=5.991

As,chi square test statistic=4.290<5.991,we fail to reject null hypothesis.

The psychologist can not conclude that some one old week infants use smell to recognize their fathers.

Observed(O) Expected(E) (O-E)^2/E 1 28 20.67 2.60 2 15 20.67 1.55 3 19 20.67 0.13 Total 62 62 4.29

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