NOTE: Missing values were generated as a result of performing an operation on missing values.Įach place is given by: (Number of times) at (Line):(Column).ġ at 692:13 1 at 693:28 1 at 694:17 1 at 695:9 1 at 697:18 1 at 697:23 NOTE: Invalid argument to function LOG(0) at line 695 column 9. Next we create a new variable which is the log of this difference.įinally, we want to create the average TCB over the three measures (and try three different methods). We also do this in one statement (without first calculating the two TCBV variables). First we calculate TCBV at each time, and simply subtract these two variables. We want to look at change in TCBV, the ratio of TCB to TCV from time 1 to time 2. We have data on brain MRI measures in six people, one measure of total cranial volume (TCV), which should not change much over time, and three measures of total brain volume (TCB). Mean(var1, var2, var3, var4) Square Root Function If a value is missing for a given observation, then the average of the non-missing variables is calculated. Missing values are treated as 0.įinds the average of the variables in parentheses. Rule 3: For operators with the same priority, operations are performed left to right except for priority 1 operations which are performed right to left.Ĭalculates the sum of the variables in parentheses. Rule 2: Operations are performed in order of priority. Rule 1: Expressions within parentheses are evaluated first. In order to understand how to create new variables using mathematical expressions in SAS we must first review the rules of operation: Mathematical Expressions and SAS Functions
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |