Data Mining -> Systems Factors  -> How Does Class-Size Measures Up

How does class-size reduction measure-up with other common educational interventions in a cost benefit analysis?

Why is this question important? Given the limited resources that are available for the education of children, it is important to select interventions that have the greatest impact that we can afford. Using Yeh's effectiveness cost ratio formulas a rough comparison can be drawn comparing class-size reduction to other educational interventions.

See further discussion below.

Source:  The Cost-Effectiveness of Five Policies for Improving Student Achievement and The Wing Institute calculations of teacher costs and effect size taken from the STAR Project

Results: When class-size reduction costs and size effects are plugged into the formula used in Yeh's 2007 study, Class-size has an effectiveness cost ratio similar to Accountability.  The class-size effectiveness cost ratio is .000221 and Accountability .000252. Both of these as well as the 10% additional spending, Vouchers, and Charter Schools under perform in comparison to Rapid Assessment. By far, Rapidly Assessment is the most cost effective intervention for improving student performance. It should be noted the analysis of class size reduction does not meet the rigorous standards that were employed in Yeh's original study, but it does offer one possible look at how we might begin to look at the affects of educational interventions.

Implications: Educational researchers might begin to match effect sizes and costs of interventions in a standardized format designed to provide stakeholders and decision makers with a practical way to compare the value of potential interventions.

Authors:  Stuart S. Yeh

Publisher: American Journal of Evaluation, 2007 (Sage Publications)

Study Description:
Yeh: See the Yeh study description for details on The Cost-Effectiveness of Five Policies for Improving Student Achievement 

The Wing Institute: The Wing Institute used Yeh's formula (effect size/cost per student = effectiveness cost ratio) to establish a effectiveness cost ratio for class-size reduction

Effect Size: 0.24875 - This was taken from the average effect size of K-3 from the STAR Project study

Cost Per student: The cost for the implementation is conservative and does not include additional supervision or facility costs. It was based solely on the cost of additional teachers. The cost of a teacher was based on 2007 The American Federation of Teachers (ATF) survey for a beginning teacher salary, $35,284. Benefits were based upon the US Department of Education calculations 2005-06 of total benefit costs at .37% of salary. The cost per student was based upon the STAR Project's class-sizes. An additional increase in teacher costs of 36% was determined by reducing class-size from an average class of 24 to 15. Based on these costs and ratios a cost per student was established at $1,123.

Definitions: 1. Rapid assessment: Systems that provide nonjudgmental testing feedback regarding student performance in subjects such as math or reading 2 to 5 times per week and immediately after each test. 2. Increased Spending: 10% increase in per-pupil expenditure. 3. Accountability: The use of high-stakes testing to hold schools accountable for improved student performance. 4. Cost of an intervention: The value of the resources that are given up by society to implement the intervention, regardless of how those costs are reported by government entities. Note: Vouchers and Charter Schools were not defined in the study. 5. Class-size: A large class for the purposes of the STAR project was 22-26 and the reduced class-size was 13-17.

Citation:
Yeh, S. S. (2007). The cost-effectiveness of five policies for improving student achievement. American Journal of Evaluation, 28(4), 416-436.

Related Research: The Cost-Effectiveness of Five Policies for Improving Student Achievement, Yeh 2007