probability

Bloomberg's brain dead brainwave

Billionaire Mayor of New York, and wannabe corporate education reformer Mike Bloomberg has suggested a radically absurd idea

he said, “you would cut the number of teachers in half but you would double the compensation of them, and you would weed out all the bad ones and just have good teachers.

“Double the class size with a better teacher is a good deal for students.”

Bloomberg's opinion is based upon a misguided and factually wrong premise, one he continues to hold to

Karen Matthews, a reporter with The Associated Press, asked, via Twitter, whether the mayor saw one teacher and 62 children as a good model. The mayor’s press secretary, Stu Loeser, shot back: “Are you asking as a journalist, advocate, or mom?”

No doubts haunt the mayor. In 2008 he insisted that class-size research was “unambiguous.”

“I don’t even understand why the subject comes up anymore,” he said, adding that all that mattered was teacher quality.

Let's examine class sizes and see if they matter. Michael C. Morrison, Ph.D. has analyzed 9,000 school districts to determine the impact on class sizes and graduation. His findings are unambiguous.

District probabilities for above average graduation performance are inversely related to district pupil-teacher ratios. As class size increases district probability for above average graduation performance decrease, controlling for district per capita income (a proxy for district socio-economic status) and district total revenue per student (a district proxy for programs and services).

Here's the graph of results

This isn't the only study of course, it's a subject that has been well and extensively researched. The National Bureau of Economic Research (NBER) found

“We find that assignment to a small class increases the probability of attending college by 2.7 percentage points, with effects more than twice as large among blacks. Among those with the lowest ex ante probability of attending college, the effect is 11 percentage points. Smaller classes increase the likelihood of earning a college degree by 1.6 percentage points and shift students towards high-earning fields such as STEM (science, technology, engineering and medicine), business and economics.”

Michael Morrison has detailed further studies on the subject, here.

As for Mayor Bloomberg, he doesn't practice what he is preaching

There’s a final oddity. Among the so-called meritocratic elite, low teacher-to-child ratios are beloved. The mayor’s daughters went to Spence, where classes hover from 10 to 15. Trinity, Dalton, Riverdale, Horace Mann: All charge $35,000 or more per year, and classes rarely exceed 12 in the lower grades.

Imagine if they packed those billionaire's kids into classrooms of 63!

Analysis shows charters underperform in Ohio's big 8

Every year, the state of Ohio releases an enormous amount of district- and school-level performance data. Since Ohio has among the largest charter school populations in the nation, the data provide an opportunity to examine performance differences between charters and regular public schools in the state.

Ohio’s charters are concentrated largely in the urban “Ohio 8” districts (sometimes called the “Big 8”): Akron; Canton; Cincinnati; Cleveland; Columbus; Dayton; Toledo; and Youngstown. Charter coverage varies considerably between the “Ohio 8” districts, but it is, on average, about 20 percent, compared with roughly five percent across the whole state. I will therefore limit my quick analysis to these districts.
[...]
In short, there are significant differences between charters and regular public schools in the likelihood that they receive different ratings, even controlling for the student characteristics mentioned above. To make things simpler, let’s take a look at how “being a charter school” affects the predicted probability of receiving ratings using three different “cutoff” points: The odds of schools receiving the rating of “continuous improvement” or better; “effective” or better; and “excellent” or better. The graph below represents the change in probability for charter schools.

The difference between the two types of schools in the probability of receiving “excellent” or better (-0.02, or two percent) is small and not statistically significant. The other two differences, on the other hand, are both large and significant. Charter schools are 13 percent less likely to receive a rating of “effective” or better, and they are 22 percent less likely to receive “continuous improvement” or better.

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