[R] grubbs test to detect all outliers

[AbouEl-Makarim Aboueissa]

*R: *Grubbs Test to detect all outliers Per group for all columns in a data
frame



Dear All: good morning

I have a dataset (as an example) with two column factors (factor1 and
factor2) and 5 numerical columns (X,Y,Z,U,V). The X and Y columns have same
length as factor1; and Z, U, and V have same length as factor2. Please see
dataset is copied below. Please note that all dataset columns have NAs
values.

*Need help on this:*


Can we use the grubbs.test() function to detect all outliers and replace it
by NA in X and Y datasets per group in factor1; and in Z, U, and V datasets
per group in factor2. Columns in the dataframe have different lengths, but
when I read the .csv file, R added NA values for the shorter columns.

If you need the .csv data file, please let me know.


Thank you very much for your help in advance.




install.packages("outliers")
library(outliers)

datafortest<-read.csv("G:/data_for_test.csv", header=TRUE)
datafortest

datafortest<-data.frame(datafortest)

datafortest$factor1<-as.factor(datafortest$factor1)
datafortest$factor2<-as.factor(datafortest$factor2)

str(datafortest)

##### tried to use grubbs.test() on a single column of the dataframe, but
still not working
tests.for.outliers.X<- grubbs.test(datafortest$X, na.rm = TRUE, type=11)


####################################

*grubbs.test() on a single dataset: but this can only detect if the min and
the max are outliers.*


xx999<-c(0.088,1,2,3,4,5,6,7,8,9,88,98,99)
grubbs.test(xx999, type=11)




With many thanks

Abou



factor1      X            Y         factor2          Z           U
  V
1     4455.077 888 1 999           NA 999
1     4348.031 333 1 475            NA 240
1    9999.789 618 1 507 252 394
1    3813.139 417 1 603 332 265
1  7512.65 344 1 442 216           NA
1     5642.667            NA 1 486 217 275
1     6684.386 341 1 927 698 479
2     5165.731 999 1 971 311 562
2 NA 265 1 388 999 512
2     3259.241 557 2 888 444 777
2     3288.383 234 2 514            NA 322
2      1997.878 383 2 409 311           NA
2       99990.61           NA 2 546 327 728
2       2655.977          NA 2 523 228 653
3      3189.49 7777 2 313 456 450
3      1826.851 287 2 296 412 576
3      4386.002 352 2 320 251         NA
3      3295.091 308 2 388 888 396.5
3      2120.902 526 3 9999 398 888
3 NA 489 3 677 438 307
3      2056.123 291 3 555 428 219
3      1995.088 444 3              NA 319           NA
3 NA 349 3 479           NA 321
3      2539.873 333 3 257 406 417
      3 313 334 409
      3 296 465 546
      3 320 180 523
      3 388 999 313



______________________


*AbouEl-Makarim Aboueissa, PhD*

*Professor, Mathematics and Statistics*
*Graduate Coordinator*

*Department of Mathematics and Statistics*
*University of Southern Maine*

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