R-Helpers, I am trying to insert a value into a dataframe. This value is a proportion calculated by counting the number of those individuals with that value and then inserting the proportion at the end of the dataframe to only those individuals with the given value. The problem I am running into is that the proportions are not being attached to only those individuals with the specified value for that proportion. Below is an example of the code that I am using. I have also attached the data file that I am using to create this dataframe. #Read in Data age.int <- read.csv('C:/intage.csv',header = TRUE) asubs112 <- subset(age.int, rs1042364 != "(2,2)") ages112 <- sort(unique(na.omit(asubs112$first_drink))) for ( i in ages112) { indce <- which(na.omit(asubs112$first_drink == i)) prop <- length(indce)/nrow(asubs112) asubs112[indce,5] <- prop asubs112[indce,] } Below is the output that I get from the script above. Notice the proportion for the first NA but not any of the others. Not sure what I am doing wrong, any suggestions are a big help. TIA, Adrian asubs112[1:50,] IND_ID rs1042364 first_drink age_int V5 4 10008007 (1,2) NA 16 0.003891051 6 10013012 (1,2) 13 14 0.116731518 7 10015006 (1,2) 12 17 0.105058366 8 10015007 (1,1) 12 16 0.105058366 10 10021009 (1,2) NA 15 NA 14 10039036 (1,2) NA 15 NA 15 10039037 (1,2) NA 13 NA 17 10045005 (1,2) 13 17 0.116731518 18 10045014 (1,2) 13 14 0.116731518 21 10055022 (1,2) NA 15 NA 22 10059006 (1,2) 12 NA 0.105058366 23 10060021 (1,2) NA 15 NA 24 10060022 (1,2) NA 13 NA 27 10069028 (1,2) 16 17 0.066147860 29 10071022 (1,1) 14 16 0.116731518 30 10071026 (1,2) NA 13 NA 31 10071028 (1,2) NA 13 NA 32 10071032 (1,2) 16 16 0.066147860 34 10072004 (1,2) 16 17 0.066147860 37 10073021 (1,2) 12 NA 0.105058366 39 10077013 (1,2) NA 14 NA 40 10077076 (1,2) 15 15 0.062256809 41 10084005 (1,2) 14 15 0.116731518 44 10088017 (1,2) 15 15 0.062256809 50 10093005 (1,2) NA NA NA 51 10096003 (1,2) 17 NA 0.023346304 56 10108005 (1,2) 14 NA 0.116731518 57 10112001 (1,2) 6 16 0.003891051 58 10114003 (1,1) 13 17 0.116731518 59 10114004 (1,1) 11 NA 0.027237354 60 10114005 (1,2) 12 14 0.105058366 61 10114006 (1,1) 13 17 0.116731518 62 10114007 (1,2) 15 15 0.062256809 63 10115006 (1,2) 13 14 0.116731518 69 10118011 (1,2) 14 14 0.116731518 70 10118012 (1,2) 16 17 0.066147860 73 10123024 (1,2) 13 15 0.116731518 76 10130019 (1,2) NA 13 NA 77 10130020 (1,2) 12 15 0.105058366 78 10130021 (1,2) NA 14 NA 87 10144039 (1,2) 12 13 0.105058366 91 10155016 (1,2) NA 13 NA 92 10156004 (1,2) 14 15 0.116731518 99 10170009 (1,2) 16 17 0.066147860 100 10171016 (1,2) NA 15 NA 104 10171027 (1,2) 13 14 0.116731518 107 10175013 (1,2) 9 16 0.011673152 108 10181013 (1,2) 11 13 0.027237354 110 10181017 (1,1) 14 16 0.116731518 111 10181024 (1,1) 16 17 0.066147860