I started following the debate on differential minimum wage for youth (15-19 year old) and adults in New Zealand. Eric Crampton has written a nice series of blog posts, making the data from Statistics New Zealand available. I will use … Continue reading →
184 search results for "ANOVA"
Calculating and graphing within-subject confidence intervals for ANOVA
Psychologists are gradually coming round to the view that it is a good idea to present interval estimates alongside point estimates of statistics. The most common statistic reported in psychology research is almost certainly the mean (strictly...
Assessing the Forecasting Ability of Our Model
Today we wish to see how our model would have faired forecasting the past 20 values of GDP. Why? Well ask yourself this: How can you know where your going, if you don't know where you've been? Once you understand please proceed on with the following post.
First recall the trend portion that we have already accounted for:
> t=(1:258)
> t2=t^2
> trendy= 892.656210 +...
Major changes to the forecast package
The forecast package for R has undergone a major upgrade, and I’ve given it version number 3 as a result. Some of these changes were suggestions from the forecasting workshop I ran in Switzerland a couple of months ago, and some have been on the drawing board for a long time. Here are the main
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...
Two-Way PERMANOVA (with Vegan-Function adonis) Using Customized Contrasts
...say you have a multivariate dataset and a two-way factorial design - you do a PERMANOVA and the aov-table (adonis is using ANOVA or "sum"-contrasts) tells you there is an interaction - how to proceed when you want to go deeper into the ana...
Model Validation: Interpreting Residual Plots
When conducting any statistical analysis it is important to evaluate how well the model fits the data and that the data meet the assumptions of the model. There are numerous ways to do this and a variety of statistical tests to evaluate deviations from model assumptions. However, there is little general acceptance of any of the statistical tests. Generally...
The foundations of Statistics: a simulation-based approach
“We have seen that a perfect correlation is perfectly linear, so an imperfect correlation will be `imperfectly linear’.” page 128 This book has been written by two linguists, Shravan Vasishth and Michael Broe, in order to teach statistics “in areas that are traditionally not mathematically demanding” at a deeper level than traditional textbooks “without using 
Additive modelling and the HadCRUT3v global mean temperature series
Earlier, I looked at the HadCRUT3vgl data set using generalized least squares to investigate whether the trend in temperature since 1995 was statistically significant. Here I want to follow-up one of the points from the earlier posting; namely using a … Continue reading →
Global warming since 1995 ‘now significant’
Yesterday (June 11, 2011) the BBC reported on comments by Prof. Phil Jones, of the Climatic Research Unit (CRU), University of East Anglia (UEA), that the warming experienced by the planet since 1995 was statistically significant. That the trend in … Continue reading →
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
