[R] Monte Carlo on simple regression

Ogbos Okike g||ted|||e2014 @end|ng |rom gm@||@com
Wed Aug 22 18:20:25 CEST 2018


Hello Eric,
Thanks for this.

I tried it. It went but another problem prevents the code from running.
 source("script.R")
Error in Li[sample(1:N, size = S, replace = TRUE), ] :
  incorrect number of dimensions

The error is coming from the line:
 subsample <- Li[sample(1:N, size=S, replace=TRUE), ]

I tried to replace Li with N but it didn't go. I also tried replacing it
with length(Li). The same error remains.

Thank so much for looking at this again.

Ogbos


On Wed, Aug 22, 2018 at 5:06 PM Eric Berger <ericjberger using gmail.com> wrote:

> Li is defined as d1$a which is a vector. You should use
>
> N <- length(Li)
>
> HTH,
> Eric
>
>
> On Wed, Aug 22, 2018 at 6:02 PM, Ogbos Okike <giftedlife2014 using gmail.com>
> wrote:
>
>> Kind R-users,
>> I run a simple regression. I am interested in using the Monte Carlo to
>> test
>> the slope parameter.
>> Here is what I have done:
>> d1<-read.table("Lightcor",col.names=c("a"))
>> d2<-read.table("CRcor",col.names=c("a"))
>>  Li<-d1$a
>> CR<-d2$a
>>
>>  fit<-lm(Li~CR)
>>  a<-summary(fit)
>> a gives the slope as 88.15
>>
>> Problem: I now what to repeat the samples to access this coefficient.
>> Following one of the related examples I got online, I did (tried to
>> modify):
>>
>> N <- nrow(Li) # returns the number of observations in the dataset
>> C <- 50         # desired number of subsamples
>> S <- 38         # desired sample size
>>
>> sumb2 <- 0
>> for (i in 1:C){   # a loop over the number of subsamples
>>   set.seed(3*i)   # a different seed for each subsample
>>   subsample <- Li[sample(1:N, size=S, replace=TRUE), ]
>>   mod <- lm(Li~CR,data=subsample)
>>   #sum b2 for all subsamples:
>>   sumb2 <- sumb2 + coef(mod)[[2]]
>> }
>> print(sumb2/C, digits = 3)
>>
>>    But when I run the script, I had error message:
>> Error in 1:N : argument of length 0
>> My data:
>> Li        CR
>> 74281 8449
>> 92473 8148
>> 62310 8520
>> 71219 8264
>> 33469 8389
>> 75768 7499
>> 61636 7821
>> 103829 8468
>> 87336 8568
>> 129443 8190
>> 97682 8539
>> 106918 8502
>> 97171 8578
>> 48012 8181
>> 93086 8631
>> 92374 8562
>> 113010 8404
>> 66956 8592
>> 133037 8632
>> 108849 8644
>> 81544 8442
>> 105072 8615
>> 143437 7724
>> 153294 7829
>> 123735 8682
>> 154738 8756
>> 100760 8839
>> 108034 8839
>> 81826 8858
>> 116901 8847
>> 80780 8869
>> 122684 8736
>> 141716 9087
>> 144315 9166
>> 162078 9147
>> 163184 9267
>> 150688 9275
>> 200848 9259
>> 221570 8943
>> 192424 8564
>> 173024 9282
>> 197326 9318
>> 209344 9293
>> 220201 9242
>> 212626 9324
>> 218115 9319
>> 170001 9314
>> 187490 9346
>> 172440 9350
>> 180330 9349
>> 200807 9355
>> 234994 9350
>> 139053 9284
>> 150048 9361
>> 203650 9346
>> 233331 9369
>> 198790 9340
>> 164060 9382
>> 198000 9401
>> 201707 9355
>> 179257 9369
>> 188736 9298
>> 243392 9393
>> 246040 9374
>> 269058 9364
>> 201657 9370
>> 187942 9354
>> 228514 9305
>> 234000 9392
>> 224431 9395
>> 163502 9398
>> I would be most glad for your great assistance.
>> Many thanks.
>> Ogbos
>>
>>         [[alternative HTML version deleted]]
>>
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>>
>
>

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