Posts Tagged ‘ Uncategorized ’

Compute the square root matrix

May 25, 2016
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Compute the square root matrix

Children in primary school learn that every positive number has a real square root. The number x is a square root of s, if x2 = s. Did you know that matrices can also have square roots? For certain matrices S, you can find another matrix X such that X*X […] The post Compute the square root matrix appeared first on The DO Loop.

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How to fit a variety of logistic regression models in SAS

May 23, 2016
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How to fit a variety of logistic regression models in SAS

SAS software can fit many different kinds of regression models. In fact a common question on the SAS Support Communities is "how do I fit a <name> regression model in SAS?" And within that category, the most frequent questions involve how to fit various logistic regression models in SAS. There […] The post How to fit a variety of logistic regression models in SAS appeared first on The DO Loop.

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All I really need to know about Newton’s method I learned in primary school

May 18, 2016
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All I really need to know about Newton’s method I learned in primary school

I was eleven years old when I first saw Newton's method. No, I didn't go to a school for geniuses. I didn't even know it was Newton's method until decades later. However, in sixth grade I learned an iterative algorithm that taught me (almost) everything I need to know about […] The post All I really need to know about Newton's method I learned in primary school appeared first on…

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The Babylonian method for finding square roots by hand

May 16, 2016
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The Babylonian method for finding square roots by hand

When I was in the sixth grade, I learned an iterative procedure for computing square roots by hand. Yes, I said by hand. Scientific calculators with a square root key were not yet widely available, so I and previous generations of children suffered through learning to calculate square roots by […] The post The Babylonian method for finding square roots by hand appeared first on The DO Loop.

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Ten tips before you run an optimization

May 11, 2016
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Ten tips before you run an optimization

Optimization is a primary tool of computational statistics. SAS/IML software provides a suite of nonlinear optimizers that makes it easy to find an optimum for a user-defined objective function. You can perform unconstrained optimization, or define linear or nonlinear constraints for constrained optimization. Over the years I have seen many […] The post Ten tips before you run an optimization appeared first on The DO Loop.

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What is a DATA step view and why is it important?

May 9, 2016
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What is a DATA step view and why is it important?

Last week I analyzed 12 million records of taxi cab transactions in New York City. As part of that analysis, I used a DATA step view to create a new variable, which was the ratio of the tip amount to the fare amount. A novice SAS programmer told me that […] The post What is a DATA step view and why is it important? appeared first on The DO Loop.

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Create a package in SAS/IML

May 4, 2016
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Create a package in SAS/IML

In a previous post I showed how to download, install, and use packages in SAS/IML 14.1. SAS/IML packages incorporate source files, documentation, data sets, and sample programs into a ZIP file. The PACKAGE statement enables you to install, uninstall, and manage packages. You can load functions and data into your […] The post Create a package in SAS/IML appeared first on The DO Loop.

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How much do New Yorkers tip taxi drivers?

May 2, 2016
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How much do New Yorkers tip taxi drivers?

When I read Robert Allison's article about the cost of a taxi ride in New York City, I was struck by the scatter plot (shown at right; click to enlarge) that plots the tip amount against the total bill for 12 million taxi rides. The graph clearly reveals diagonal and […] The post How much do New Yorkers tip taxi drivers? appeared first on The DO Loop.

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Packages: A new way to share SAS/IML programs

April 27, 2016
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Packages: A new way to share SAS/IML programs

My previous post highlighted presentations at SAS Global Forum 2016 that heavily used SAS/IML software. Several of the authors clearly want to share their work with the wider SAS analytical community. They include their SAS/IML program in an appendix or mention a web site or email address from which the […] The post Packages: A new way to share SAS/IML programs appeared first on The DO Loop.

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Matrix computations at SAS Global Forum 2016

April 25, 2016
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Matrix computations at SAS Global Forum 2016

Last week I attended SAS Global Forum 2016 in Las Vegas. I and more than 5,000 other attendees discussed and shared tips about data analysis and statistics. Naturally, I attended many presentations that featured using SAS/IML software to implement advanced analytical algorithms. Several speakers showed impressive mastery of SAS/IML programming […] The post Matrix computations at SAS Global Forum 2016 appeared first on The DO Loop.

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