Accuracy of Individual Scores: STAR Accuracy Guide

	How Accurate are the STAR Scores for Individual Students? An interpretive guide.
		David Rogosa Stanford University rag@stat.stanford.edu

	The goal here is to apply some common-sense descriptions of accuracy to the numbers or classifications that are used to indicate student achievement in STAR .

	National Percentile Ranks Version 2.0 August, 2003: CAT/6 Survey, CTB/McGraw-Hill Version 1.0 August, 1999: Stanford 9, Harcourt CRESST Technical Report 509A

	Education Week Article October 6, 1999 Stanford Report Questions Accuracy of Tests New York Times Column, September 13, 2000 How Tests Can Drop The Ball

	California Standards Tests (CST) Version 3.0 August, 2004: California Standards Tests: Math, ELA 2002, 2003. direct downland: llclassify computational function


	Also. If you have a liking for reliability coefficients, try out the shoe-shopping example

	Supporting Materials: Percentile Rank Scores Many informal statements and references in the NPR Accuracy Guides are given explicit, mathematical definition in two CRESST Technical Reports released in concert with the Version 1.0 Accuracy Guide. So for those who might be interested in technical details and underpinnings for these calculations, the two related CRESST Technical Reports are 1. Accuracy of Individual Scores Expressed in Percentile Ranks: Classical Test Theory Calculations CRESST Technical Report 509, September, 1999 2. Accuracy of Year-1, Year-2 Comparisons Using Individual Percentile Rank Scores: Classical Test Theory Calculations CRESST Technical Report 510, September, 1999