It works! Do you wanna post this as an answer in StackExchange? So that I can give you an upvote :)
This works fine
d = Import["~/Downloads/new_heart_data.csv"]; testData = d[[2 ;;, {2, 5, 8}]] // Select[FreeQ[#, "NA"] &];
Thanks! I removed all the NA rows. but when I run the testData = data[[2 ;;, {2, 5, 8}]] , I got this error -- Part::take: Cannot take positions 2 through -1 in d.
testData = data[[2 ;;, {2, 5, 8}]]
Part::take: Cannot take positions 2 through -1 in d.
Crossposted here.
