wtest {season} | R Documentation |
Tests for a seasonal pattern in Binomial data.
wtest(cases,offset,data,alpha=0.05)
cases |
variable name for cases (“successes”). |
offset |
variable name for at-risk population (“trials”). |
data |
data frame (optional). |
alpha |
significance level (default=0.05). |
A test of whether monthly data has a sinusoidal seasonal
pattern. The test has low power compared with the
cosinor
test.
test |
test statistic. |
pvalue |
p-value. |
Adrian Barnett a.barnett<at>qut.edu.au
Walter, S.D., Elwood, J.M. (1975) A test for seasonality of events with a variable population at risk. British Journal of Preventive and Social Medicine 29, 18–21.
Barnett, A.G., Dobson, A.J. (2010) Analysing Seasonal Health Data. Springer.
data(stillbirth) # tabulate the total number of births and the number of stillbirths freqs<-table(stillbirth$month,stillbirth$stillborn) data<-list() data$trials<-as.numeric(freqs[,1]+freqs[,2]) data$success<-as.numeric(freqs[,2]) # test for a seasonal pattern in stillbirth test<-wtest(cases=success,offset=trials,data=data)