[R] Defining function help
Duncan Murdoch
murdoch.duncan at gmail.com
Fri Jan 31 20:16:54 CET 2014
On 31/01/2014 12:29 PM, Mathew Nagendran wrote:
> Hello everyone. I am quite new to R and I would appreciate some help in figuring out what I am doing wrong.
>
> For the following code:
>
> > #with cost
> >
> > m.control=c(1.45,9.40,9.96,4.2,1.86,0.2)
> > m.sham=c(3.39,23.94,23.62,10.08,2.99,1.09)
> >
> > t.control=function(m, a){(1-exp(-a*m)*(1-(1/30)*m))}
> > t.sham=function(m, a, d){(1-exp(-a*(1-d)*m)*(1-(1/30)*m))}
> >
> > t.sham(2, 2, 0.1)
> [1] 0.9744979
> > t.control(2, 2)
> [1] 0.9829054
> >
> > #without cost
> >
> > m.control=c(1.45,9.40,9.96,4.2,1.86,0.2)
> > m.sham=c(3.39,23.94,23.62,10.08,2.99,1.09)
> >
> > t.control=function(m, a){(1-exp(-a*m))}
> > t.sham=function(m, a, d){(1-exp(-a*(1-d)*m))}
> >
> > t.sham(2, 2, 0.1)
> [1] 0.9726763
> > t.control(2, 2)
> [1] 0.9816844
>
> As you can see the values I am getting for t.control and t.sham are larger in the "with cost" scenario and this shouldn't be the case. (the cost is 1-1/30*m). Is there something wrong I did when defining t.sham and t.control in the "with cost" section that I am failing to see?
You aren't reading your parentheses correctly. In the first case you're
multipling only the exp() part by the cost, so you
are subtracting a smaller number from 1, hence you get a larger result.
Duncan Murdoch
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