Articles by Nick Horton

Example 8.11: violin plots

October 26, 2010 | Nick Horton

We've continued to get useful feedback and ideas from our posts on the combination dotplot/boxplot and other ways to craft similar displays. Another notion is the violin plot, which combines a boxplot and a (doubled) kernel density plot. While the ba...
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Example 8.3: pyramid plots

August 30, 2010 | Nick Horton

Pyramid plots are a common way to display the distribution of age groups in a human population. The percentages of people within a given age category are arranged in a barplot, often back to back. Such displays can be used distinguish males vs. femal...
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Second year of entries!

June 28, 2010 | Nick Horton

Hello, readers new and old!We started adding examples a year ago, in advance of the book's publication. To mark the occasion, we're closing chapter 7 and starting chapter 8 next week. We've crafted a listing of all entries from the first year and mad...
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Example 7.41: hazard function plotting

June 14, 2010 | Nick Horton

As we continue with our series on survival analysis, we demonstrate how to plot estimated (smoothed) hazard functions. RWe will utilize the routines available in the muhaz package. Background information on the methods can be found in K.R. Hess, D.M....
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Example 7.40: Nelson-Aalen plotting

June 7, 2010 | Nick Horton

In our previous entry, we described how to calculate the Nelson-Aalen estimate of cumulative hazard. In this entry, we display the estimates for the time to linkage to primary care for both the treatment and control groups in the HELP study.RWe use the...
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Augmented support for complex survey designs in R

March 3, 2010 | Nick Horton

We'll get back to code examples later this week, but wanted to let you know about an R package with updated functionality in the meantime.The appropriate analysis of sample surveys requires incorporation of complex design features, including stratification, clustering, weights, and finite population correction. These can be address in ...
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Example 7.22: the Knapsack problem

January 13, 2010 | Nick Horton

The website describes a fanciful trip by a traveler to Shangri La. They can take as many as they want of three valuable items, as long as they fit in a knapsack. The knapsack will hold no more than 25 weight units, and no more ...
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Example 7.17: The Smith College diploma problem

November 12, 2009 | Nick Horton

Smith College is a residential women's liberal arts college in Northampton, MA that is steeped in tradition. One such tradition is to give each student at graduation a diploma at random (or more accurately, in a haphazard fashion). At the end of the ceremony, a diploma circle is formed, and ...
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Example 7.16: assess robustness of permutation test to violations of exchangeability assumption

October 24, 2009 | Nick Horton

Permutation tests (section 2.4.3) are a form of resampling based inference that can be used to compare two groups. A simple univariate two-group permutation test requires that the group labels for the observations are exchangeable under the null hypothesis of equal distributions, but allows relaxation of specific distributional assumptions required by ...
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