Tag Archives: education

New free online course from Stanford: Statistics in Medicine

Leave a reply

Yesterday I received an e-mail inviting me to the following online course, offered through Stanford University’s online learning platform:

This course aims to provide a firm grounding in the foundations of probability and statistics. Specific topics include:

1. Describing data (types of data, data visualization, descriptive statistics)
2. Statistical inference (probability, probability distributions, sampling theory, hypothesis testing, confidence intervals, pitfalls of p-values)
3. Specific statistical tests (ttest, ANOVA, linear correlation, non-parametric tests, relative risks, Chi-square test, exact tests, linear regression, logistic regression, survival analysis; how to choose the right statistical test)

The course focuses on real examples from the medical literature and popular press. Each week starts with “teasers,” such as: Should I be worried about lead in lipstick? Should I play the lottery when the jackpot reaches half-a-billion dollars? Does eating red meat increase my risk of being in a traffic accident? We will work our way back from the news coverage to the original study and then to the underlying data. In the process, students will learn how to read, interpret, and critically evaluate the statistics in medical studies.

The course also prepares students to be able to analyze their own data, guiding them on how to choose the correct statistical test and how to avoid common statistical pitfalls. Optional modules cover advanced math topics and basic data analysis in R.

I think it sounds like a great way to teach introductory statistics, mainly because of the “teasers” idea.

Value-added assessments

Leave a reply

I posted about value-added assessments when the front page story in the New York Times came out early this year. In recent weeks I’ve come across a couple interesting commentaries on these scores.

At the Washington Post, Jay Mathews wrote a column titled “Devaluing value-added assessments.” I read it closely, but couldn’t understand what Mathews is saying is wrong with these scores. He begins by saying he will relate “the best argument against value-added I have seen in some time.”

Point #1:

“I have seen this sham firsthand over many years,” Wiggins writes. “Lots of so-called good N.J. and N.Y. suburban districts are truly awful when you look firsthand (as I have for three decades) at the pedagogy, assignments and local assessments; but those kids outscore the kids from Trenton and New York City, even though both city systems have a number of outstanding schools and teachers.”

I don’t get this–don’t value added scores only measure changes within a single district? Aren’t we only using them to assess teachers within districts?

Point #2:

Also, Wiggins wrote, valid research on value-added exposes “hidden truths,” such as “it IS true that models accurately predict over a three-year period, performance at the extremes. Thus, the really effective teachers stay so and the really ineffective ones are really ineffective.”

I don’t understand this at all. What is the hidden truth here exactly? That teachers matter?

Point #3:

Schools with high test scores discover through value-added analysis that they need more than that. One outstanding prep school, Wiggins said, gave a professionally designed test of critical thinking to freshmen and seniors. There was no improvement. Similar results have come from colleges giving the Collegiate Learning Assessment of analytical skills, given to freshmen and seniors.

Huh? It sounds like Mathews is saying here that value added scores help schools identify bigger problems. Isn’t that a good thing?

Point #4:

Our mistake was thinking this valuable long-term research tool would work as a one-year teacher rating system. “It becomes like a sick game of telephone: What starts out as a reasonable idea, when whispered down the line to people who don’t really get the details — or don’t want to get them — becomes an abomination,” Wiggins wrote. “By looking at individual teachers, over only one year (instead of the minimum three years as the psychometricians and VAM [valued-added model] designers stress), we now demand more from the tests than can be obtained with sufficient precision.”

I’m not sure what to make of this. It sounds like the critique is that the VA measure only uses change over one year. I suppose that would be problematic if true, but I’m not sure it is true. Even if it is, the paper by Chetty et al. (subject of the NYT article linked above) offers evidence that VA measures are an unbiased measure of quality.

A second commentary comes from Andrew Gelman’s blog. This is more of a technical discussion about whether VA measures make the right modeling assumptions.

How racially segregated are America’s schools?

Leave a reply

David Kirp’s opinion piece in the New York Times argues that (1) efforts to racially de-segregate America’s schools have been abandoned, perhaps since 1974, and (2) this is bad for education policy outcomes, because integrated schools have been associated with better outcomes for black students.

But I’m more interested in the premise–is it the case that America’s public schools are still racially segregated? Are they more or less segregated than in 1974? 1954?

As they sometimes do, the Times followed up on the post with a “Room for Debate” feature. The discussion is, as far as I can tell, is about Kirp’s claim (2) above, but the introductory paragraph has links to a couple articles about segregation in two cities, New York and Charlotte, N.C.

Potpourri

Leave a reply
  • “Top 0.1%, By Zip Code”
  • “Big Super PAC donors: Same old guns, just more money”
  • Causal effects of the Head Start program
  • New York Times mentions confidence intervals (in the context of value-added teacher ratings)
  • Social benefit of obesity: less crime?

    • “City Students at Small Public High Schools Are More Likely to Graduate, Study Says”

    Leave a reply

    NY Times reports:

    But Michael Mulgrew, president of the United Federation of Teachers, questioned whether there were other factors that might explain the higher graduation rate in the small schools, like fewer special education students or better attendance records for those entering the small schools, since attendance rates have been shown to be an indicator of on-time graduation.

    “I’m very happy for any school that is graduating students,” Mr. Mulgrew said. “But a study that is trying to say that one particular type of school is better than the other without looking at all the relevant factors is disingenuous.”

    Gordon Berlin, president of MDRC, said the lottery process ensured that there were comparable numbers of special education students and English-language learners represented in both groups of students being tracked. He said attendance records for the students prior to high school were also comparable, and would not have affected the results.

    “No Obesity Link to Junk Food in Schools”

    Leave a reply

    NY Times reports:

    Researchers at Pennsylvania State University tracked the body mass indexes of 19,450 students from fifth through eighth grade. In fifth grade, 59 percent of the children attended a school where candy, snacks or sugar-sweetened beverages were sold. By eighth grade, 86 percent did so.

    The researchers compared children’s weight in schools where junk food was sold and in schools where it was banned. The scientists also evaluated eighth graders who moved into schools that sold junk food with those who did not, and children who never attended a school that sold snacks with those who did. And they compared children who always attended schools with snacks with those who moved out of such schools.

    No matter how the researchers looked at the data, they could find no correlation at all between obesity and attending a school where sweets and salty snacks were available.

    “Crystal clear” correlation between long school days and student outcomes is not causal

    Leave a reply

    Scott Lehigh in the Boston Globe: On charter time: A longer school day transforms low-income kids into high achievers.

    Drawing on recent state test score (MCAS) data, Lehigh notes that charter schools, which have longer school days than public schools, are doing better in terms of scores. He then muses that

    At this point, several things should be crystal clear to everyone.

    First, more learning time can transform low-income kids into high achievers. Second, charters, which offer a significantly longer day for the same per pupil expense, are a bargain for taxpayers. Third, incremental change in the traditional schools will no longer suffice.

    But there are two big problems. One is that there are presumably several things about charter schools that distinguish them from public schools, beyond the length of the school day. No attempt is made here to separate out the independent effect of school day length. More importantly, there is the huge selection effect: students who enroll in charter schools are different, probably in terms of being more motivated to achieve, than those who don’t.

    Ok, so I’m just shooting fish in a barrel, right? But it still seems problematic that this is what passes for informed debate when it comes to education policy. I don’t assume to know how education policy develops, but it seems safe to assume that the Boston Globe editorial pages are an important factor.

    NY Times article on single-sex education kerfuffle

    Leave a reply

    A group of education scholars and psychologists is crying “pseudoscience.”

    While some studies have found better outcomes from single-sex schools, the article said, the purported advantages disappear when outcomes are corrected for pre-existing differences. For example, Chicago’s Urban Prep Charter Academy for Young Men, a school whose high college admissions rates were praised this year by Secretary of Education Arne Duncan, was subsequently criticized by the scholar Diane Ravitch as having test results that were actually lower than average on basic skills.

    “This is very much a live issue, and I think it’s snowballing,” said Galen Sherwin, a staff lawyer for the Women’s Rights Project of the A.C.L.U., who is handling the Louisiana case. “I see news stories every single week about new proposals, usually based on the idea that boys and girls learn differently. Often it’s people who have attended training programs by Sax or Gurian, saying these programs will cater to boys’ and girls’ specific learning styles.”

    More here.

    NYT story on classroom tech and student outcomes

    Leave a reply

    The district leaders’ position is that technology has inspired students and helped them grow, but that there is no good way to quantify those achievements — putting them in a tough spot with voters deciding whether to bankroll this approach again.

    “My gut is telling me we’ve had growth,” said David K. Schauer, the superintendent here. “But we have to have some measure that is valid, and we don’t have that.”

    It gives him pause.

    “We’ve jumped on bandwagons for different eras without knowing fully what we’re doing. This might just be the new bandwagon,” he said. “I hope not.”

    I think that about sums up the story. But we can throw in this excerpt too, which seems to be the extent of the actual reportage on the (lack of) data:

    Many studies have found that technology has helped individual classrooms, schools or districts. For instance, researchers found that writing scores improved for eighth-graders in Maine after they were all issued laptops in 2002. The same researchers, from the University of Southern Maine, found that math performance picked up among seventh- and eighth-graders after teachers in the state were trained in using the laptops to teach.

    A question plaguing many education researchers is how to draw broader inferences from such case studies, which can have serious limitations. For instance, in the Maine math study, it is hard to separate the effect of the laptops from the effect of the teacher training.

    (Emphasis added.) Interesting to contrast the spending on technology with the cuts to teachers, and the role of accountability and evaluation in each case, which the article also does at times.