Posts Tagged ‘ Data Analysis ’

Merge observed outcomes into a list of all outcomes

July 1, 2015
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Merge observed outcomes into a list of all outcomes

When you count the outcomes of an experiment, you do not always observe all of the possible outcomes. For example, if you roll a six-sided die 10 times, it might be that the "1" face does not appear in those 10 rolls. Obviously, this situation occurs more frequently with small […] The post Merge observed outcomes into a list of all outcomes appeared first on The DO Loop.

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The spiral of splatter

June 11, 2015
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The spiral of splatter

"Daddy, help! Help me! Come quick!" I heard my daughter's screams from the upstairs bathroom and bounded up the stairs two at a time. Was she hurt? Bleeding? Was the toilet overflowing? When I arrived in the doorway, she pointed at the wall and at the floor. The wall was […] The post The spiral of splatter appeared first on The DO Loop.

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The mystery of the density curve that was too short

June 3, 2015
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The mystery of the density curve that was too short

I was reading a statistics book when I encountered a histogram that caught my eye. The histogram looked similar to the one at the left. It contained a normal density estimate overlaid on a histogram, but the height of the density curve seemed too short when compared to the heights […] The post The mystery of the density curve that was too short appeared first on The DO Loop.

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SAS/IML functions that operate on columns of a matrix

June 1, 2015
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SAS/IML functions that operate on columns of a matrix

A SAS programmer asked for a list of SAS/IML functions that operate on the columns of an n x p matrix and return a 1 x p row vector of results. The functions that behave this way tend to compute univariate descriptive statistics such as the mean, median, standard deviation, and quantiles. The following […] The post SAS/IML functions that operate on columns of a matrix appeared first on The DO Loop.

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No major hurricanes have hit the US coast recently. Lucky us!

May 14, 2015
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No major hurricanes have hit the US coast recently. Lucky us!

Perhaps you saw the headlines earlier this week about the fact that it has been nine years since the last major hurricane (category 3, 4, or 5) hit the US coast. According to a post on the GeoSpace blog, which is published by the American Geophysical Union (AGU), researchers ran […] The post No major hurricanes have hit the US coast recently. Lucky us! appeared first on The DO Loop.

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Create and use a permutation matrix in SAS

April 29, 2015
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Create and use a permutation matrix in SAS

Suppose that you compute the correlation matrix (call it R1) for a set of variables x1, x2, ..., x8. For some reason, you later want to compute the correlation matrix for the variables in a different order, maybe x2, x1, x7,..., x6. Do you need to go back to the […] The post Create and use a permutation matrix in SAS appeared first on The DO Loop.

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Finding observations that match a target value

March 18, 2015
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Finding observations that match a target value

Imagine that you have one million rows of numerical data and you want to determine if a particular "target" value occurs. How might you find where the value occurs? For univariate data, this is an easy problem. In the SAS DATA step you can use a WHERE clause or a […]

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Analyzing the first 10 million digits of pi: Randomness within structure

March 12, 2015
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Analyzing the first 10 million digits of pi: Randomness within structure

Saturday, March 14, 2015, is Pi Day, and this year is a super-special Pi Day! This is your once-in-a-lifetime chance to celebrate the first 10 digits of pi (π) by doing something special on 3/14/15 at 9:26:53. Apologies to my European friends, but Pi Day requires that you represent dates […] The post Analyzing the first 10 million digits of pi: Randomness within structure appeared first on The DO Loop.

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Plotting multiple time series in SAS/IML (Wide to Long, Part 2)

February 27, 2015
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Plotting multiple time series in SAS/IML (Wide to Long, Part 2)

I recently wrote about how to overlay multiple curves on a single graph by reshaping wide data (with many variables) into long data (with a grouping variable). The implementation used PROC TRANSPOSE, which is a procedure in Base SAS. When you program in the SAS/IML language, you might encounter data […]

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Plotting multiple series: Transforming data from wide to long

February 25, 2015
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Plotting multiple series: Transforming data from wide to long

Data. To a statistician, data are the observed values. To a SAS programmer, analyzing data requires knowledge of the values and how the data are arranged in a data set. Sometimes the data are in a "wide form" in which there are many variables. However, to perform a certain analysis […]

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