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...
Monthly Archives: August 2011
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 ...
Accelerating path-dependent loops: A quick Rcpp case study
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...
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 
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 →
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...
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 →
Experiences with using SAS and R in insurance and banking
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...
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...
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...
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
