In a study of children with a particular disorder, parents were asked to rate th
ID: 2935251 • Letter: I
Question
In a study of children with a particular disorder, parents were asked to rate their child on a variety of items related to how well their child performs different tasks. One item was "Has difficulty organizing work," rated on a five-point scale of 0 to 4 with 0 corresponding to "not at all" and 4 corresponding to "very much." The mean rating for 289 boys with the disorder was reported as 2.25 with a standard deviation of 1.17. (Round your answers to four decimal places.) Compute the 90% confidence interval. , Compute the 95% confidence interval. , Compute the 99% confidence interval. , Explain the effect of the confidence level on the width of the interval. We see that the width of the interval does not change with confidence level. We see that the width of the interval decreases with confidence level. We see that the width of the interval increases with confidence level.
Explanation / Answer
We see than width of the interval increases with confidence interval
mean 2.25 std.dev. 1.17 n 289 SE = std.dev./sqrt(n) 0.0688 90% CI z-value 1.6449 ME = z*SE 0.1132 Lower Bound = mean - ME 2.1368 Upper Bound = mean + ME 2.3632 Width = UB - LW 0.2264 95% CI z-value 1.9600 ME = z*SE 0.1349 Lower Bound = mean - ME 2.1151 Upper Bound = mean + ME 2.3849 Width = UB - LW 0.2698 99% CI z-value 2.5758 ME = z*SE 0.1773 Lower Bound = mean - ME 2.0727 Upper Bound = mean + ME 2.4273 Width = UB - LW 0.3546