Another Way to Look at the Tier System (and more data!)
My apologies, this is a data-heavy one but I love getting new data to dwell over….
**For those who hate data, the gist is that for the Tier spots, Tier 4 kids do not get their “fair share” of spots based on the share of kids who are ELIGIBLE for the spots. However including the Rank and Tier spot, Tier 4 kids get slightly more than their “fair share.” (I put this in quotes as people may disagree on what constitutes the fair share.)**
Selective Prep has issued this piece that discusses some of the conclusions about applicants by Tier. Based on Tier assignments, they conclude that it is hard for Tier 4 kids to get a spot than lower Tier kids. The data shows quite definitively that Tier 4 kids come into the process with higher scores than the lower tier kids do. Draw your own conclusions about nurture and or nature (CPS.) In any case, either you conclude that poor kids are genetically inferior and/or slackers or that they are somehow getting the short end of the stick when it comes to preparing for high school applications.
So based on the % of kids who qualify to take the SE test, i normalized the breakout to include all spots (rank and tier) and the qualified applicants break out as 1/2/3/4 21%/23%/26%/30%. Not actually too bad for those Tier 1-2 kids. Based on all the beefing I’d have thought it would be more skewed.towards. This is awesome math as I don’t think we’ve seen these “qualified numbers” so far. So based on the TIER spots, the Tier 4kids have 30% of the pool gunning for 17.5% of the spots. The “quirk” as SPrep points out.
However comparing this to WBEZ’s overall SE share by tier 20%/20%/26%/35% we see that the shares by qualified Tier applicants fall out pretty closely, with kids in Tier 4 actually having a BETTER shot at an SE spot than any other tier (thanks to the rank spots, not the tier spots which ARE tougher for tier 4 kids to get.)
Press release from SelectPrep below:
Matthew Greenberg (312) 409-8411
March 15, 2012
A QUIRK OF THE TIER SYSTEM: MORE APPLICANTS IN HIGHER TIERS
|Chicago, ILUnder the current admissions system for Chicago’s Selective Enrollment High Schools and Academic Centers, it is much more difficult for a qualified Tier 4 student to land a spot than it is for a qualified Tier 1 student, for one simple reason – there are many more qualified Tier 4 students than Tier 1 students, yet each Tier gets the same allotment of Selective Enrollment and Academic Center seats.CPS has divided the city into four Tiers, with each Tier representing one quarter of the school-age population. CPS currently gives each Tier exactly one quarter of the seats (after the first 30%, based on scores only, have been allotted). But one quarter of the school-age population is not the same as one quarter of the qualified school-age population.
To qualify to take the Selective Enrollment Exam as an 8th grader – and be eligible to apply to a Selective Enrollment High School — a student must score a minimum of stanine 5 (e.g., above 40%) in both Reading and Math on his/her 7th grade standardized test. Since far fewer Tier 1 students reach the 40th percentile than their Tier 4 counterparts, the pool of qualified Tier 1 students is much smaller than the pool from Tier 4. And since both Tiers are allotted the same number of seats, a qualified applicant from Tier 1 faces far less competition than does a qualified Tier 4 student.
An analysis of CPS data reveals that the bottom of the 5th stanine (40th percentile) is virtually the same as the minimum ISAT score selected for “meets or exceeds” standards. According to CPS, approximately 56% of Tier 1 7th graders were at or above the 5th stanine and thus eligible to take the Selective Enrollment Entrance Exam, while approximately 81% of all Tier 4 7th graders were qualified to take the Exam as shown in Figure 1.
Figure 1. Calculating “Qualified School-Age Students” by Tier (Selective Enrollment)
To see how this affects the slots that are allocated across the Tiers, we then eliminated unqualified students from the population – since they cannot be applicants. We find that although 25% of the school-age population is in Tier 4, 30% of all qualified students are in Tier 4. Similarly Tier 1 contains 25% of the school-age population, but 21% of qualified students. If each qualified student were to have an equal chance at a Selective Enrollment slot, then 21% of the slots (70% of the Tier slots multiplied by 30% — the percent of qualified students) should be allocated to Tier 4 students vs. the current 17.5% and only 14.7% (70% of the Tier slots multiplied by 21%) vs. the current 17.5% should be allocated to Tier 1 students. This re-allocation would then provide each qualified applicant with an equal chance. These calculations are shown in Figure 2 below.
Figure 2. Admissions Based on Qualified Applicants (Selective Enrollment)
Academic Center Admissions
Since it’s harder to qualify to take the Academic Center Admissions Test, the results get more pronounced if one considers the Academic Center admissions process. Only a 6th grader who scores a minimum of 70% on both Reading and Math on his/her 5th grade standardized test can apply to an Academic Center. As shown in Figure 3 below, only 36% of Tier 1 students are qualified to apply to an Academic Center, while 64%of Tier 4 students are qualified.
If each qualified student were to have an equal chance at an Academic Center spot, then 23.8% of the slots (70% of the Tier slots multiplied by 34% — the percent of qualified students) should be allocated to Tier 4 students vs. the current 17.5% and only 12.6% (70% of the Tier slots multiplied by 18%) vs. the current 17.5% should be allocated to Tier 1 students.
Figure 3. “Qualified School-Aged Students” by Tier (Academic Center)
Behind the Numbers (Academic Center Admissions)
We used the average ISAT performance (translated into a scaled score) provided by CPS for each Tier and assumed that the performance of each Tier’s student population was normally distributed.
The mean math score of all CPS 5th graders is 223, with a standard deviation of 27, so the 70th percentile yields a score of 237. So any 5th grader must get a 237 to take the Academic Center Test. In Tier 1, the 56% ISAT score implies a mean score of 227, meaning that only 36% qualified to take the Academic Center Test. In Tier 4, the ISAT mean score of 81% implies a Tier 4 mean score of 247, which means that 64% are qualified.
If CPS were to provide each qualified student with an equal chance of getting selected for a Selective Enrollment High School and Academic Center respectively — note that Tier 4 would receive 3.5% more spots in Selective Enrollment High Schools and 6.3% more Academic Center spots. At the same time Tier 1 would receive 2.8% fewer Selective Enrollment and 4.9% fewer Academic Center spots.
Let’s look at an example to see how this may affect a particular school. Suppose that Lane Tech has 1,000 total seats (although there are actually more), this would mean that Tier 4 students would receive 21% of these spaces for a total of 210 slots vs. the current 175, which would provide Tier 4 students with an additional 35 spaces.
To read more, click here.
Background: About the Tier System
Thirty percent of the seats at any of the selective schools are awarded based on a student’s academic performance in comparison with other students citywide. The remaining seventy percent of seats are awarded to students based on their test scores and grades in comparison with other students in their socio-economic Tier, with each Tier receiving 17.5% of the slots.
CPS has grouped each of the City of Chicago’s 874 census tracts into four Tier Groups based on 6 socio-economic factors: median family income, percentage of owner occupied homes, percentage of single family households, adult educational level, percentage of non-English speakers, and school quality. Census tracts deemed to have more favorable socio-economic factors are grouped into higher Tiers and tracts with less favorable ones are grouped into lower Tiers. Any student in the City of Chicago is grouped into a specific Tier based on his/her home address – and how the census tract that this address falls into has been rated by CPS.
SelectivePrep was founded by test prep veterans with over 25 years of test preparation experience – and extensive backgrounds in both classroom teaching and curriculum development. SelectivePrep offers the only classroom program that prepares students for both of the standardized tests needed to gain admission to a Selective Enrollment High School and the Academic Center. SelectivePrep knows what it takes to train and motivate students who are intent upon gaining admission to one of the nine Chicago Selective Enrollment High Schools or one of seven Academic Centers. SelectivePrep’s programs provide a thorough and rigorous review of test content, so students can approach these competitive admissions processes with confidence.
For additional information and registration go to www.selectiveprep.com or call (312) 409-8411.