Question: Deficits in speech acquisition often occur when a child has hearing difficulty or is slow to develop the motor functions associated with speech. Other deficits in speech acquisition are of unknown origin. Males generally develop physiologically at a slower rate than females, & in a recent large study of speech development in young children, investigators hypothesized that a greater proportion of boys would have speech deficits for this reason. A random sample of healthy two-year-olds was followed over the course of a year. At age 3, each child was classified as having a speech delay or not.
Gender
|
Speech delay
|
No speech Delay
|
Total
|
Male
|
22
|
280
|
302
|
Female
|
78
|
259
|
337
|
Total
|
100
|
539
|
639
|
Let π1 & π2 be the proportion of males who have a speech delay & the proportion of females who have a speech delay, respectively. At the 0.05 significance level do the data provide evidence of the hypothesized developmental differences?