The teacher noticed that 13 out of 20 girls read 90 words per minute by the end of the second grade, while only 9 out of 17 boys showed the same result. Interpret the following output produced by the Shiny app "Bootstrap Confidence Interval for Difference in Two Proportions".

Question

The teacher noticed that 13 out of 20 girls read 90 words per minute by the end of the second grade, while only 9 out of 17 boys showed the same result. ​ Interpret the following output produced by the Shiny app "Bootstrap Confidence Interval for Difference in Two Proportions". ​  ​

Quizplus · Accepted Answer

The output from the Shiny app gives a bootstrap confidence interval for the difference in two proportions. In this case, the proportions are the proportion of girls and boys who read at least 90 words per minute. The interval (-0.21, 0.44) means that there is a 95% probability that the true population mean difference in proportion (girls minus boys) falls between -0.21 and 0.44. This means that it is possible that the proportion of girls who read at least 90 words per minute is 21% lower than the proportion of boys, or it is 44% higher than the proportion of boys. However, we cannot say with certainty that the true population mean difference falls within this interval, because it is just an estimate based on the sample data. Therefore, choice C is the best answer.

The Teacher Noticed That 13 Out of 20 Girls Read