Question

Belsky, Weinraub, Owen, and Kelly (2001) reported on the effects of preschool childcare on the development of young children. One result suggests that children who spend more time away from their mothers are more likely to show behavioral problems in kindergarten. Using a standardized scale, the average rating of behavioral problems for kindergarten children is μ=35. A sample of n=49 kindergarten children who had spent at least 20 hours per week in childcare during the previous year produced a mean score of 42.7 with a standard deviation of 6. Is there enough evidence to support that children who spend more time away from their mothers are more likely to show behavioral problems in kindergarten? To answer this, conduct a full hypothesis test using the one-sample t-test (alpha of α=0.05, two-tailed test), including a measure of effect size.

critical values

final t answer

Answer 1

null hypothesis: Alternate Hypothesis: 2.011 for 0.05 level with two tailed test and n-1=48 degree of freedom, critical value of t= Decision rule: reject Ho if absolute value of test statistic t >2.011 population mean sample mean sample size sample std deviation 35 42.700 49.00 6.000 standard error of mean = Sx=s/vn= 0.8571 test statistic t = (x-1)/sx= 8.983

critical t values = -2.011 , 2.011

test statistic t value =8.983

reject Ho and conclude that there is enough evidence to support that children who spend more time away from their mothers are more likely to show behavioral problems in kindergarten

effect size :

Cohen's d=|μ-μo|/σ =

1.28