Hi See the file http://www.mijnbestand.nl/Bestand-6ZPTBYDLBZQI.txt here . That file contains the results of a study on breathing resistance in children with asthma and children with cystic fibrosis to investigate wheter there is a relationship between breathing resistance and length in each of the two groups. Consider the cystic fibrosis group.
See the http://www.mijnbestand.nl/Bestand-G68PRQKUB4QX.txthttp://www.mijnbestand.nl/Bestand-G68PRQKUB4QX.txt R-code for what I have now I already have respectivly: a) QQplot with best fit line of resistance against length, b) investigation linear relationship with a t-test, linear regression line (see QQplot at part A), c) testing with a different test statistic, and than the two question I find hard: To perform the tests in parts b and e, it was assumed that the measurement errors are normally distributed. Test with a suitable QQ-plot whether or not this assumption is justified. Recall that the residuals of a linear regression can be considered as approximations of the actual measurement errors. And: What is, based on all your results, your final conclusion about the relationship between breathing resistance and length? I think it has to do something with the Central Limit Theorem? -- View this message in context: http://r.789695.n4.nabble.com/QQplot-normally-distributed-tp4633819p4633927.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
