Monthly Archives: August 2011

Z-Tests: Should we even bother?

August 23, 2011
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Z-Tests: Should we even bother?

Should statistical teachers continue to teach z-tests?vote:  save z-test, or stop z-testLooking at textbooks, articles and general research I cannot remember the last time I saw someone use a z-test in a study. I have seen many a t-test, ANOVA, ch...

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Graphically analyzing variable interactions in R

August 23, 2011
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Graphically analyzing variable interactions in R

I studied Ecology as an undergraduate, which meant I spent a lot of time gathering and analyzing field data. One of the basic tools we used to look for relationships in a large set of variables was correlation and scatterplot matrices. Each of these ...

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Accelerating path-dependent loops: A quick Rcpp case study

August 23, 2011
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User BobH asked on StackOverflow about accelerating path-dependent loops. He provided a simple example in which a vector gets filled conditional on the value of the preceding element. Simple to code, but hard to vectorise. By the time I saw that q...

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Anonymising data

August 23, 2011
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Anonymising data

There are only three known jokes about statistics in the whole universe, so to complete the trilogy (see here and here for the other two), listen up: Three statisticians are on a train journey to a conference, and they get chatting to three epidemiologists who are also going to the same place. The epidemiologists are

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Time Series Analysis and Mining with R

August 23, 2011
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Time Series Analysis and Mining with R

Time series data are widely seen in analytics. Some examples are stock indexes/prices, currency exchange rates and electrocardiogram (ECG). Traditional time series analysis focuses on smoothing, decomposition and forecasting, and there are many R functions and packages available for those … Continue reading →

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Random input software testing

August 23, 2011
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Random input software testing

The usual approach to testing software is to create a specific problem and see if the software gets the correct answer.  Although this is very useful, there are problems with it: It is labor-intensive It almost totally neglects to test the code that throws errors There can be unconscious bias in the test cases created … Continue reading...

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Experiences with using SAS and R in insurance and banking

August 23, 2011
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Experiences with using SAS and R in insurance and banking

In July 2011, Hong Ooi presented an engaging talk to Melbourne R Users Group. Both David Smith from Revolutions and Eugene Dubossarsky behind the Analyst First movement have discussed the presentation. The video of the talk is now available for … Continue reading →

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Experiences with using SAS and R in insurance and banking

August 23, 2011
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Hong Ooi talks about some of the more interesting projects that he has used R for in the last year. These include fitting models for mortgage loss given default, a Monte Carlo application for stress-testing loan portfolios (in combination with Excel an...

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A warning on the R save format

August 23, 2011
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A warning on the R save format

The save() function in the R platform for statistical computing is very convenient and I suspect many of us use it a lot. But I was recently bitten by a “feature” of the format which meant I could not recover my data. I recommend that you save data in a data format (e.g. CSV or CDF), not using...

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A warning on the R save format

August 23, 2011
By
A warning on the R save format

The save() function in the R platform for statistical computing is very convenient and I suspect many of us use it a lot. But I was recently bitten by a “feature” of the format which meant I could not recover my data. I recommend that you save data in a data format (e.g. CSV or CDF), not using...

Read more »