Palimpsest

Evolving notes, images and sounds by Luis Apiolaza

Page 47 of 64

Careless comparison bites back (again)

When running stats labs I like to allocate a slightly different subset of data to each student, which acts as an incentive for people to do their own work (rather than copying the same results from a fellow student). We also need to be able to replicate the results when marking, so we need a record of exactly which observations were dropped to create a particular data set. I have done this in a variety of ways, but this time I opted for code that looked like:

setwd('~/Dropbox/teaching/stat202-2012')

biom <- read.csv('biom2012.csv', header = TRUE)
drops <- read.csv('lab4-dels.csv', header = TRUE)

# Use here your OWN student code
my.drop <- subset(drops, student.code == 'mjl159')
my.data <- subset(biom, !(id %in% my.drop))

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Early August flotsam

Back teaching a couple of subjects and it’s the constant challenge to find enough common ground with students so one can push/pull them to the other side of new concepts. We are not talking about complex hierarchical models using mixed models or Bayesian approaches, but multiple linear regression or similar. What do students actually learn in first year stats…?

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Digital heritage

Digital TV and clothes in Bairro Alto, Lisbon, Portugal.

Split-plot 2: let’s throw in some spatial effects

Disappeared for a while collecting frequent flyer points. In the process I ‘discovered’ that I live in the middle of nowhere, as it took me 36 hours to reach my conference destination (Estoril, Portugal) through Christchurch, Sydney, Bangkok, Dubai, Madrid and Lisbon.

Where was I? Showing how split-plots look like under the bonnet (hood for you US readers). Yates presented a nice diagram of his oats data set in the paper, so we have the spatial location of each data point which permits us playing with within-trial spatial trends.
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