Posts Tagged ‘ pseudo-random numbers ’

Pseudo-Random vs. Random Numbers in R

November 25, 2011
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Pseudo-Random vs. Random Numbers in R

Happy Thanksgiving, everyone. Earlier today, I found an interesting post from Bo Allen on pseudo-random vs random numbers, where the author uses a simple bitmap (heat map) to show that the rand function in PHP has a systematic pattern and compares these to truly random numbers obtained from random.org. The post’s results suggest that pseudo-randomness in PHP is

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Example 8.35: Grab true (not pseudo) random numbers; passing API URLs to functions or macros

April 19, 2011
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Example 8.35: Grab true (not pseudo) random numbers; passing API URLs to functions or macros

Usually, we're content to use a pseudo-random number generator. But sometimes we may want numbers that are actually random-- an example might be for randomizing treatment status in a randomized controlled trial.The site Random.org provides truly rando...

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Example 7.23: the Monty Hall problem

January 20, 2010
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Example 7.23: the Monty Hall problem

The Monty Hall problem illustrates a simple setting where intuition often leads to a solution different from formal reasoning. The situation is based on the game show Let's Make a Deal. First, Monty puts a prize behind one of three doors. Then the player chooses a door. Next, (without moving the pize) Monty opens an...

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Example 7.21: Write a function to simulate categorical data

January 8, 2010
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Example 7.21: Write a function to simulate categorical data

In example 7.20, we showed how to simulate categorical data. But we might anticipate needing to do that frequently. If a SAS function weren't built in and an equivalent R function not available in a package, we could build them from scratch.SASThe SAS code is particularly tortured, since we must parse the parameter string to extract the...

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Example 7.20: Simulate categorical data

January 4, 2010
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Example 7.20: Simulate categorical data

Both SAS and R provide means of simulating categorical data (see section 1.10.4). Alternatively, it is trivial to write code to do this directly. In this entry, we show how to do it once. In a future entry, we'll demonstrate writing a SAS Macro (section A.8.1) and a function in R (section B.5.2) to do it...

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