Posts Tagged ‘ simulate data ’

Example 9.7: New stuff in SAS 9.3– Frailty models

September 27, 2011
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Example 9.7: New stuff in SAS 9.3– Frailty models

Shared frailty models are a way of allowing correlated observations into proportional hazards models. Briefly, instead of l_i(t) = l_0(t)e^(x_iB), we allow l_ij(t) = l_0(t)e^(x_ijB + g_i), where observations j are in clusters i, g_i is typically norma...

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Example 7.30: Simulate censored survival data

March 30, 2010
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Example 7.30: Simulate censored survival data

To simulate survival data with censoring, we need to model the hazard functions for both time to event and time to censoring. We simulate both event times from a Weibull distribution with a scale parameter of 1 (this is equivalent to an exponential ra...

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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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