[R] Monte Carlo on simple regression

[Ogbos Okike]

Hello Erick,

Thanks again.
Another line indicated error:

source("script.R")
Error in eval(predvars, data, env) :
  numeric 'envir' arg not of length one
Thank you for additional assitance.
Ogbos



On Wed, Aug 22, 2018 at 5:23 PM Eric Berger <ericjberger using gmail.com> wrote:

> You have an extra comma ... it should be
>
> Li[sample(1:N, size = S, replace = TRUE)]
>
> i.e. no comma after the closing parenthesis
>
>
>
> On Wed, Aug 22, 2018 at 7:20 PM, Ogbos Okike <giftedlife2014 using gmail.com>
> wrote:
>
>> 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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