Statistical Horizons Blog


What’s So Special About Logit?

For the analysis of binary data, logistic regression dominates all other methods in both the social and biomedical sciences. It wasn’t always this way. In a 1934 article in Science, Charles Bliss proposed the probit function for analyzing binary data, and that method was later popularized in David Finney’s 1947 book Probit Analysis. For many […]

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Imputation by Predictive Mean Matching: Promise & Peril

Predictive mean matching (PMM) is an attractive way to do multiple imputation for missing data, especially for imputing quantitative variables that are not normally distributed. But, as I explain below, it’s also easy to do it the wrong way.  Compared with standard methods based on linear regression and the normal distribution, PMM produces imputed values […]

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Getting the Lags Right

In my November and December posts, I extolled the virtues of SEM for estimating dynamic panel models. By combining fixed effects with lagged values of the predictor variables, I argued that this approach offers the best option for making causal inferences with non-experimental panel data. It controls for all time-invariant variables, whether observed or not, […]

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More on Causal Inference With Panel Data

This is a follow-up to last month’s post, in which I considered the use of panel data to answer questions about causal ordering: does x cause y or does y cause x?  In the interim, I’ve done many more simulations to compare the two competing methods, Arellano-Bond and ML-SEM, and I’m going to report some […]

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Using Panel Data to Infer Causal Direction: ML vs. Arellano-Bond

Does x cause y or does y cause x? Virtually everyone agrees that cross-sectional data are of no use in answering this question. The ideal, of course, would be to do two randomized experiments, one examining the effect of x on y, and the other focused on the reverse effect. Absent this, most social scientists […]

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Sensitivity Analysis for Not Missing at Random

When I teach my seminar on Missing Data, the most common question I get is “What can I do if my data are not missing at random?” My usual answer is “Not much,” followed by “but you can do a sensitivity analysis.” Everyone agrees that a sensitivity analysis is essential for investigating possible violations of […]

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Problems with the Hybrid Method

For several years now, I’ve been promoting something I called the “hybrid method” as a way of analyzing longitudinal and other forms of clustered data. My books Fixed Effects Regression Methods for Longitudinal Data Using SAS (2005) and Fixed Effects Regression Models (2009) both devoted quite a few pages to this methodology. However, recent research […]

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Free SAS!

Let me tell you about my favorite new toy, the SAS® University Edition, which was just released on May 28. It’s essentially free SAS for anybody who wants it, and it has the potential to be a real game changer. SAS has long had a reputation for being one of the best statistical packages around, but […]

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Prediction vs. Causation in Regression Analysis

In the first chapter of my 1999 book Multiple Regression, I wrote “There are two main uses of multiple regression: prediction and causal analysis. In a prediction study, the goal is to develop a formula for making predictions about the dependent variable, based on the observed values of the independent variables….In a causal analysis, the […]

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Listwise Deletion: It’s NOT Evil

At the 1998 Annual Meeting of the American Political Science Association, Gary King and three co-authors presented a paper titled “Listwise deletion is evil: What to do about missing data in political science.” The paper was later published under a different title in the American Political Science Review, but the original title has stuck in my head […]

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