# Calculator 3

One way of gauging the achievement gap for college readiness is to track student’s math achievement, the strongest predictor of college entrance and academic success. Imagine an American student in P-12 schools who wants to go to college for associates degree or bachelor’s degree. Given his current math achievement (as measured by national standardized test score and percentile rank), what is the chance of his future success for 2-year or 4-year college entrance and completion?

Building on national math achievement growth trajectories, we can assess student achievement gap relative to college readiness benchmarks. The calculator below provides two metrics of the achievement gap: Cohen’s d and Lee & Finn’s d΄ (see calculator 1 for information on d΄).

Based on the national norms of math achievement from NAEP, ECLS-K and NELS data, we convert percentile rank (i.e., percent students in the U.S. performing at or below the math achievement score of this hypothetical American student) into an estimate of cumulative math achievement scores (in standard deviation units) from the point of Kindergarten entry through the end of grade that you choose. For example, the score of 6 for grade 4 math means that the student's achievement from Kindergarten through grade 4 in math is about six standard deviation units. This estimated score of achievement will be displayed along with college readiness benchmark values on P-12 math achievement growth curve chart below.

Then we calculate standardized achievement gap (d) between actual and desired achievement for chosen educational goal and translate that into time-indexed gap (d΄). The value of d captures how much the student’s math achievement deviates from the goal of being on-track toward chosen educational goal in standard deviation units. Positive values of d mean that the child is on track toward the goal, whereas negatives values of d mean that the child is not on track. Further, this calculator also computes time-indexed gap d΄for corresponding d values to show how much time the child is ahead or behind in terms of the years/months of learning (e.g., 3.5 = 3 years and 5 months ahead; -2.1 = 2 years and 1 month behind). In short, d and d΄ would measure practical significance of achievement gaps for college readiness in both standard deviation and school time units respectively.