Blog Archives

Kaplan-Meier Survival Plot – with at risk table

November 5, 2011
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Kaplan-Meier Survival Plot – with at risk table

Credit for the bulk of this code is to Abhijit Dasgupta and the commenters on the original post here from earlier this year. I have made a few changes to the functionality of this which I think warrant sharing. A brief … Continue reading →

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Latent class mixed models – with graphics

October 2, 2011
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Latent class mixed models – with graphics

Foreword Apologies that the output isn’t showing well as far as spacing and alignment is concerned. Am working on fixing that! Background Generally when we have a set of data, we have known groupings. Be that three different treatment groups, … Continue reading →

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Children height and blood pressure z-scores

September 20, 2011
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Children height and blood pressure z-scores

Following on from some of my earlier posts, this is purely about, hopefully, saving some other people some time in putting this together. Height z-scores are required to then calculate the blood pressure z-scores. The CDC (Center for Disease Control … Continue reading →

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2011 Perth City to Surf Stats

September 6, 2011
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2011 Perth City to Surf Stats

Like every year, August sees the thousands taking part in the Perth City to Surf, and with that comes the chance for some stats. Why? Curiosity more than anything, and to convince myself that my time in the 12km run … Continue reading →

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ICD code – search looping

July 15, 2011
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ICD code – search looping

Following on from my earlier post on creating a table of ICD codes in R, here is how I am currently counting these codes and storing the codes in a dataframe: Firstly create a dataframe to store the results in: hosp_count <- as.data.frame(matrix(ncol=length(icd_codes))) names(hosp_count) <- names(icd_codes) Counting Occurences: Then start to loop through your dataset with

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ICD codes – Analysing hospitilisations

July 14, 2011
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ICD codes – Analysing hospitilisations

A brief first post on what I hope will be a series of posts on analysing hospitilisation data, which is recorded using ICD codes (International Statistical Classification of Diseases and Related Health Problems) Initially here is an R file. This can be read in and will create a list, 218 long, forming groupings using sub

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gridExtra – Multiple plots from ggplot2

June 8, 2011
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gridExtra – Multiple plots from ggplot2

Thanks to this great post http://www.imachordata.com/?p=730 we can now put multiple plots on a display with ggplot2. This provides somewhat similar functionality to ‘par(mfrow=c(x,y))’ which would allow multiple plots with the base plot function. gridExtra doesn’t have quite the same level of options as ‘par’, but the syntax is simple. grid.arrange( graph1, graph2, ncol=2 Simple. ‘grid.table’

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Generating unique random IDs

June 7, 2011
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Generating unique random IDs

Recently I was asked to help create random IDs for someone. At first I thought, ‘Ah yup, 1:x (1,2,3, …,x), job done’. Then I thought that there had to be a R function/package to create better looking IDs, to which I didn’t find one, if there is, please let me know. In the mean time

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More on logging the outcome

March 4, 2011
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More on logging the outcome

This one does my head in. I do it fairly regularly, lots of people do, but I find everytime it comes to interpreting the results I have to slow it right down and go step by step. Answer: When you log the outcome, then on the original scale, for all else constant, Y will be

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Anova – Type I/II/III SS explained

March 2, 2011
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Anova – Type I/II/III SS explained

Not my post, just bookmarking this. It’s from http://goanna.cs.rmit.edu.au/~fscholer/anova.php ANOVA (and R) The ANOVA Controversy ANOVA is a statistical process for analysing the amount of variance that is contributed to a sample by different factors. It was initially derived by R. A. Fisher in 1925, for the case of balanced data (equal numbers of observations

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