Trend since 1998—significant??
I had a question sent to me about the trend since 1998. As many of you know, my last post included an analysis which showed that the linear regression trend since 1998 was statistically significant. Trends versus start year. Error bars are the 95% confidence intervals. My questioner asked if I had accounted for autocorrelation in my analysis. The short answer is "No, I did not." The reason? According to my analysis, it wasn't necessary. Here are my methods and R code. #Get coverage-corrected HadCRUT4 data and rename the first two columns CW<-read.table("http://www-users.york.ac.uk/~kdc3/papers/coverage2013/had4_krig_annual_v2_0_0.txt", header=F) names(CW)<-"Year" names(CW)<-"Temp" #Analysis for autocorrelation—I check manually as well but so far the auto.arima function has performed admirably. library(forecast) auto.arima(resid(lm(Temp~Year, data=CW, subset=Year>=1998)), ic=c("bic")) The su