Substitute Shift: How Data Can Address Equitable Substitute Placement

SDP Fellow Megan LaneIn Chicago Public Schools, an increased demand for substitutes significantly disadvantages some schools. SDP Fellow Megan Lane looks to the data to find out why. 

Substitute teachers play a vital role in the functioning of schools and education of students. Yet in a district like Chicago Public Schools (CPS), the third largest district in the U.S., daily requests for substitute teachers can number in the thousands. During school year 2015-2016, for example, the average number of daily requests for substitutes numbered over 1,500. In school year 2017-2018, this average was over 1,700. And while daily requests increased, fill percentages dropped, leaving an average of 350 requests unfilled each day.

Even though the number of active substitutes exceeded daily requests by over 1,000, substitute preferences about when and where they sub resulted in inequitable fill rate patterns across the city and over time. This is why in 2018, SDP Fellow Megan Lane looked to the data to understand sub preferences, identify high-need schools with low fill rates, and develop a stipend program to incentivize substitute teachers to work in high-need schools.

“What we had was not an issue with the pool of substitutes,” explained Lane. “We had a fairly large pool. This issue was that substitutes were finding and frequenting preferred schools, leaving a subset of schools with a revolving door of different substitutes or simply no substitutes at all.” The data revealed that substitutes preferred to take jobs close to where they live or in schools where they felt they had a greater amount of support—criteria that often left high-need schools out.

The thought, then, was that if the district incentivized substitutes toward those high-need schools with an increased stipend, they would see a more even dispersal of coverage. To determine how these stipends were distributed, CPS used a weighted metric that combined historical fill rates and current fill rates to identify the 75 highest-need schools. Those schools were then further split into three sub-groups of 25 schools each in order of highest to lowest priority within high-need ranking. Substitutes that took teaching jobs in Tier 1 schools (highest priority) were paid an extra $40 per day, whereas substitutes taking jobs in Tiers 2 and 3 were paid an additional $35 and $30 per day, respectively.

And indeed, the stipends were successful in increasing fill rates in high-need schools. Yet, after implementing the stipends and revisiting the data, Lane uncovered a slightly discouraging truth.

“While we found that fill rates went up in the stipend schools,” said Lane, “we were surprised to see more of a shifting behavior than an increase in the pool. Both the fill rates in non high-need schools and the fill rates overall went down.” Fill rates in schools outside the “high-need” designation dropped from an average of 84% in the 2017-18 school year to 75% in 2018-19. Given that this pool represented 85% of the schools in the district, the stipend program presented a truly double-edged sword.

As with most data projects, the results of this analysis were nuanced and included several factors outside the scope of the stipend program. District-wide requests for substitutes continued to increase in the 2018-19 school year, and requests in high-need schools increased at a greater rate—requests in high-need schools increased by 30%, which those in non high-need schools only increased by 7%. And while the stipend program helped keep pace with the increased requests, it may also have funneled substitutes out of non high-need schools, which saw a 3% drop in fill rates compared to the previous year.

The impact of projects such as Lane’s is significant. Teacher absences and vacant classrooms adversely affect school climate, threaten student safety, disrupt routines, and distract from teaching and learning[1]. Couple this fact with the manifold challenges facing already vulnerable schools and populations, and the effects compound. Thus, Lane and her team didn’t want to reverse the positive impact of this policy on high-need schools, which were most often the schools serving non-white students who qualified for free or reduced meal pricing and had an average of 3.0 school quality points.

Thus, they recommended continuing the stipend, albeit conditionally. Additionally, Lane and her team recommended offering benefits to subs who meet a minimum frequency criteria to incentivize substitutes to take on more assignments overall. A number of other recommendations were also made to address coverage on high-demand days, increase the pool of available subs, to empower subs to improve the culture of subbing, and to reduce the amount of teacher absences.

Ultimately, Lane will be building on this project to directly address the impact of teacher absences on student achievement. “We’re looking at student achievement next,” Lane explains, “to connect the dots to explain the impact of teacher absences and sub fill rates on students and school systems.” And with an average of 350 sub requests each day in CPS, the insights of her empirical analysis will be paramount.

While balancing substitute distribution is vital in the short term for CPS, long-term fixes to this issue require a deeper understanding of why teacher absences are so high in the first place. Thus Lane, alongside SDP Faculty Advisor and Brown University Faculty Matt Kraft, is now taking this project further to examine why teachers are absent, how absences impact the need for substitutes, and how students are ultimately affected by this larger issue.

Megan Lane, Ph. D., is the Senior Manager of Teacher Retention at Chicago Public Schools.



[1] Herrmann, M. A., & Rockoff, J. E. (2012). Worker Absence and Productivity: Evidence from Teaching. Journal of Labor Economics, 30(4), 749-782. 

Miller, R. (2012). Teacher Absence as a Leading Indicator of Student Achievement: New National Data Offer Opportunity to Examine Cost of Teacher Absence Relative to Learning Loss. Center for American Progress.

Hess, R.S., & Copeland, E. P. (2001). Students’ stress, coping strategies, and school completion: A longitudinal perspective. School Psychology Quarterly, 16, 389-405.