# Blog Archives

## Example 7.8: Plot two empirical cumulative density functions using available tools

August 1, 2009
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The empirical cumulative density function (CDF) (section 5.1.16) is a useful way to compare distributions between populations. The Kolmogorov-Smirnov (section 2.4.2) statistic D is the value of x with the maximum distance between the two curves. As an...

## Book now shipping from Amazon

July 27, 2009
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Amazon now reports that the book is in stock! The current discount is 13%.Or, order from the publisher. If you are an ASA member, you can use the online discount code 634LH to obtain a 15% discount.

## Example 7.7: Tabulate binomial probabilities

July 25, 2009
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Suppose we wanted to assess the probability P(X=x) for a binomial random variate with n = 10 and with p = .81, .84, ..., .99. This could be helpful, for example, in various game settings. In SAS, we ﬁnd the probability that X=x using differences in t...

## Example 7.6: Find Amazon sales rank for a book

July 20, 2009
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In honor of Amazon's official release date for the book, we offer this blog entry.Both SAS and R can be used to find the Amazon Sales Rank for a book by downloading the desired web page and ferreting out the appropriate line. This code is likely to br...

## Example 7.5: Replicating a prettier jittered scatterplot

July 15, 2009
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The scatterplot in section 7.4 is a plot we could use repeatedly. We demonstrate how to create a macro (SAS, section A.8) and a function (R, section B.5) to do it more easily.SAS%macro logiplot(x=x, y=y, data=, jitterwidth=.05, smooth=50);data lp1;set...

## Example 7.4: A prettier jittered scatterplot

July 2, 2009
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The plot in section 7.3 has some problems. At the very least, the jittered values ought to be between 0 and 1, so the smoothed lines ﬁt better with them. Once again we use the data generated in section 7.2 as an example. For both SAS and R, we use conditioning (section 1.11.2) to make the jitter happen...

## Example 7.3: Simple jittered scatterplot with smoother for dichotomous outcomes with continuous predictors

June 24, 2009
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It's useful to look at scatterplots even when the "y" variable is dichotomous. For example, this can help determine whether categorization or linear assumptions would be more plausible. However, an unmodified scatterplot is less than helpful, since all of the "y" values are either 0 or 1, and are hard to separate visually. Some jittering...

## Book now discounted 33% at Amazon!

June 24, 2009
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Our book, SAS and R: Data Management, Statistical Analysis, and Graphics, is discounted by a full third at Amazon. With free shipping! Also, they claim if it is further discounted before it ships, they'll give you the reduced price.

## Example 7.2: Simulate data from a logistic regression

June 13, 2009
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It might be useful to be able to simulate data from a logistic regression (section 4.1.1). Our process is to generate the linear predictor, then apply the inverse link, and finally draw from a distribution with this parameter. This approach is useful in that it can easily be applied to other generalized linear models. In this...