In an era of severe educational cutbacks, it would be comforting if school days could be reduced without sacrificing learning outcomes. Perhaps we could shave a week or two off the school year and the academic competency of students would not be affected.

A just-released report by Sacramento State professors Su Jin Jez and Robert Wassmer dashes any such comforting hopes. Their study offers sobering implications about the consequences of reducing K-12 school days. Jez and Wassmer prepared their report for the state Senate's Office of Research under the faculty research fellows program, which provides small amounts of support to California State University faculty for studies directly relevant to concerns of policymakers. The program is administered by Sacramento State's Center for California Studies.

Jez and Wassmer examined the effects of differences in instructional minutes at hundreds of California public school sites. Schools traditionally have varied significantly in the amount of instructional time. However, relatively little information has been gathered about such differences. Jez and Wassmer constructed a data set that included such information as well as test scores and many other characteristics of schools relevant to how their students perform on standardized tests.

Using rigorous statistical analysis, Jez and Wassmer found that, on average, the lower the number of instructional minutes at a school, the lower were the school's standardized test scores as summarized by its Academic Performance Index score. The API has become the common metric for judging differences in academic performance at California's public K-12 school sites. Parents frequently use API scores to make decisions about where to send their children and even where to live.

In short, API scores have come to represent "the big story" about how public school students are doing. Minutes in school make a difference for such rankings. Furthermore, Jez and Wassmer determined that such differences occurred even after controlling for the influence of other variables such as school racial and ethnic characteristics, portion of English language learners, poverty, average parental education, portion of credentialed teachers and enrollment makeup.

The size of the effect of cutting school minutes was notable if not huge. Consider the idea of reducing the school year by one week. This was an idea widely floated prior to Gov. Jerry Brown's recent decision about how to handle budgetary "trigger cuts." Jez and Wassmer conservatively estimated that, on average, such a reduction would lead to about an 8-point drop in a typical school's API score. To place this in context, a drop of 7 percentage points in the portion of fully credentialed teachers at a school site is needed to produce such a large decrease in the API score.

More disturbing still, Jez and Wassmer found especially pronounced effects of reducing instructional time for disadvantaged students. The California Department of Education defines such students as having both parents without a high school degree and/or the student receiving a reduced-price or free lunch. The researchers determined that for these students alone, shaving a week from the school calendar would lead to an average of an 11-point drop in API scores. So our neediest students – those most at risk of dropping out – would be hurt the most by reducing school days.

Instructional time matters. Policymakers should pay close attention to the evidence contained in the Jez and Wassmer report. It has long been known that a great many factors influence student performance. Many of these are outside the direct control of policymakers. These factors have much more to do with larger socioeconomic trends, community characteristics and parental traits. But legislators, governors and school boards can directly influence the amount of instructional time for students.

The report suggests a clear way to characterize the idea that we can shave a few days here and there from the school calendar without harming learning outcomes. We should call that "wishful thinking."

© Copyright The Sacramento Bee. All rights reserved.

Edward L. Lascher Jr. is an associate dean at California State University, Sacramento, and acting director of the Center for California Studies.

• Read more articles by Edward L. Lascher Jr.