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...yrius.com> To: r-help at stat.math.ethz.ch Subject: [R] quadratic trends and changes in slopes I'd like to use linear and quadratic trend analysis in order to find out a change in slope. Basically, I need to solve a similar problem as discussed in http://www.gseis.ucla.edu/courses/ed230bc1/cnotes4/trend1.html .... RESPONSE: This message updates my earlier response. I just started programming with R on Friday and I wanted to make my response to you more general... before starting on a more difficult problem of the same type at work. The two improvements I've added are: (1) a more genera...

...yrius.com> To: r-help at stat.math.ethz.ch Subject: [R] quadratic trends and changes in slopes I'd like to use linear and quadratic trend analysis in order to find out a change in slope. Basically, I need to solve a similar problem as discussed in http://www.gseis.ucla.edu/courses/ed230bc1/cnotes4/trend1.html .... RESPONSE: Since I'm in the process of switching from SAS to R, this was a good exercise for me. An R program to work the example you cited is appended. I hope this meets your needs. Chuck White # R program for working example at: # http://www.gseis.ucla.edu/courses/ed230bc1...

I'd like to use linear and quadratic trend analysis in order to find out a change in slope. Basically, I need to solve a similar problem as discussed in http://www.gseis.ucla.edu/courses/ed230bc1/cnotes4/trend1.html My subjects have counted dots: one dot, two dots, etc. up to 9 dots. The reaction time increases with increasing dots. The theory is that 1 up to 3 or 4 points can be counted relatively fast (a process known as "subiziting") but that is becomes slower at around 5 dots (&quot...