Posts Tagged ‘ Getting Started ’

6 ways to use the _NULL_ data set in SAS

June 11, 2018
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6 ways to use the _NULL_ data set in SAS

In SAS, the reserved keyword _NULL_ specifies a SAS data set that has no observations and no variables. When you specify _NULL_ as the name of an output data set, the output is not written. The _NULL_ data set is often used when you want to execute DATA step code [...] The post 6 ways to use the _NULL_ data set in SAS appeared first on The DO Loop.

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6 easy ways to specify a list of variables in SAS

May 29, 2018
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6 easy ways to specify a list of variables in SAS

The SAS language provides syntax that enables you to quickly specify a list of variables. SAS statements that accept variable lists include the KEEP and DROP statements, the ARRAY statement, and the OF operator for comma-separated arguments to some functions. You can also use variable lists on the VAR statements [...] The post 6 easy ways to specify a list of variables in SAS appeared first on The DO Loop.

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Position items in a grid

May 21, 2018
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Position items in a grid

In a recent blog post, Chris Hemedinger used a scatter plot to show the result of 100 coin tosses. Chris arranged the 100 results in a 10 x 10 grid, where the first 10 results were shown on the first row, the second 10 were shown on the second row, and so [...] The post Position items in a grid appeared first on The DO Loop.

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The sweep operator: A fundamental operation in regression

April 18, 2018
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The sweep operator: A fundamental operation in regression

The sweep operator performs elementary row operations on a system of linear equations. The sweep operator enables you to build regression models by "sweeping in" or "sweeping out" particular rows of the X`X matrix. As you do so, the estimates for the regression coefficients, the error sum of squares, and [...] The post The sweep operator: A fundamental operation in regression appeared first on The DO Loop.

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The chi-square test: An example of working with rows and columns in SAS

April 2, 2018
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The chi-square test: An example of working with rows and columns in SAS

As a general rule, when SAS programmers want to manipulate data row by row, they reach for the SAS DATA step. When the computation requires column statistics, the SQL procedure is also useful. When both row and column operations are required, the SAS/IML language is a powerful addition to a [...] The post The chi-square test: An example of working with rows and columns in SAS appeared first on The…

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How to use FIRST.variable and LAST.variable in a BY-group analysis in SAS

February 26, 2018
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How to use FIRST.variable and LAST.variable in a BY-group analysis in SAS

My article about the difference between CLASS variables and BY variables in SAS focused on SAS analytical procedures. However, the BY statement is also useful in the SAS DATA step where it is used to merge data sets and to analyze data at the group level. When you use the [...] The post How to use FIRST.variable and LAST.variable in a BY-group analysis in SAS appeared first on The DO…

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The difference between CLASS statements and BY statements in SAS

February 14, 2018
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The difference between CLASS statements and BY statements in SAS

When I first learned to program in SAS, I remember being confused about the difference between CLASS statements and BY statements. A novice SAS programmer recently asked when to use one instead of the other, so this article explains the difference between the CLASS statement and BY variables in SAS [...] The post The difference between CLASS statements and BY statements in SAS appeared first on The DO Loop.

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What is rank correlation?

August 14, 2017
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What is rank correlation?

When someone refers to the correlation between two variables, they are probably referring to the Pearson correlation, which is the standard statistic that is taught in elementary statistics courses. Elementary courses do not usually mention that there are other measures of correlation. Why would anyone want a different estimate of [...] The post What is rank correlation? appeared first on The DO Loop.

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The IFN function versus the IF-THEN/ELSE statement in SAS

June 7, 2017
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The IFN function versus the IF-THEN/ELSE statement in SAS

I have previously discussed how to define functions that safely evaluate their arguments and return a missing value if the argument is not in the domain of the function. The canonical example is the LOG function, which is defined only for positive arguments. For example, to evaluate the LOG function [...] The post The IFN function versus the IF-THEN/ELSE statement in SAS appeared first on The DO Loop.

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A simple trick to construct symmetric intervals

April 10, 2017
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A simple trick to construct symmetric intervals

Many intervals in statistics have the form p ± δ, where p is a point estimate and δ is the radius (or half-width) of the interval. (For example, many two-sided confidence intervals have this form, where δ is proportional to the standard error.) Many years ago I wrote an article [...] The post A simple trick to construct symmetric intervals appeared first on The DO Loop.

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