CDE incorporates the use of “confidence intervals” and upper “confidence limits” in making AYP determinations. What does this mean?
Confidence intervals have important and positive implications for a schools or districts opportunity to make AYP. CDE uses a specific formula (developed by Ghosh) to calculate confidence intervals around a proportion or percentage (see Glass & Hopkins, 3rd Edition, 1996, p. 326). When using confidence intervals, upper and lower limits around the percent proficient are calculated, creating a range of values within which there is confidence that the true percentage lies. CDE will use a 95 percent confidence level, meaning that we are 95 percent confident that the percent proficient for a school or district falls within the limits determined by the confidence interval formula. For example, lets say the percent of AYP proficient students in reading at an elementary school is 82.68 and the upper and lower limits of the 95 percent confidence interval are 89.54 and 75.82, respectively. Given that the proficiency target for elementary reading is 88.46 percent, the school would be considered to
