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Tag: NHANES

Visualizing a Continuous by Continuous Interaction in Linear Regression

Visualizing a Continuous by Continuous Interaction in Linear Regression

View high res version here. “Did you see if there was a difference by [insert the person’s favorite population or topic of interest].” With a resigned response I reply “No I haven’t, but that is a good idea.” I’ve had this exchange in every research talk I’ve given. Often times we are interested in understanding how one group varies by another when predicting an outcome. This can be examined via an interaction term in a regression model. An interaction term…

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How to Use Survey Weights in R

How to Use Survey Weights in R

Survey weights are common in large-scale government-funded data collections. For example, NHIS and NHANES are two large scale surveys that track the health and well-being of Americans that have survey weights. These data collections use complex and multi-stage survey sampling to ensure that results are representative of the U.S. population. Although use of survey weights is sometimes contested in regression analyses, they are needed for simple means and proportions. The general guidance is that if analysts can control for the…

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Using a Forest Plot to Display Regression Results

Using a Forest Plot to Display Regression Results

View high res version here. How many times have you sat through a presentation and stared blankly at a table of regression results? If you have been to my presentations, it has been many, many times. I was thinking about a better and more intuitive way to present regression results that also gives a sense of uncertainty. In this post, I show how to visualize OLS regression results via a forest plot. The nice thing about forest plots is that they…

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Visualizing Body Mass Index by Percent of the Federal Poverty Level

Visualizing Body Mass Index by Percent of the Federal Poverty Level

View high res version here. It is often assumed that low-income populations have worse health outcomes. This is correct for many health outcomes, but for one, it isn’t as clear: Body Mass Index (BMI). BMI doesn’t show a clear association with income. Given that we are in the midst of an obesity epidemic, and BMI is the primary measurement of obesity, this is quite interesting. I wanted to take a look at some recent data to visualize the association. I created…

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