topic Re: Calculate Percentage incorrect ?? in SAS Enterprise Guide

Calculate Percentage incorrect ??

pcfriendly — Tue, 15 Oct 2013 02:34:19 GMT

Hi,

I'm using SAS EG 4.3 with Windows 7 & am trying to perform a calculation of a % of a Currency amount.

Example, I have 2 Fileds on a table, Sales (Currency) & Allocation (%) - NOTE the datatypes appear as shown ie; $ & %.

I go to Query Builder >> Add the 2 Fields to the Builder >> go to Add Computed Column >> Select Advanced Expression & enter;

t1.Sales*Allocation.

The figures for this example are Currency is $180.00 & the Percentage is 22%.

The result for 22% of $180.00 should be $39.60 but I am getting $38.74 ??

I then reloaded my % Field as a Number datatype & tried the below;

t1.Sales*(Allocation/100) same result ...

My goal is to apply the % Allocation figure against the sales figure to get the % of the Sales in this new Column.

Any help appreciated.

Re: Calculate Percentage incorrect ??

Tom — Tue, 15 Oct 2013 03:15:46 GMT

From the $ amount you are getting it looks the percentage is less than 22% and it is just being rounded in your display.

s=180 p=0.22 n=39.6

s=180 p=0.2152222222 n=38.74

Re: Calculate Percentage incorrect ??

pcfriendly — Tue, 15 Oct 2013 03:18:38 GMT

Thanks Tom,

The number is being entered as 22 though?

Is there a way to make it not round the number?

Re: Calculate Percentage incorrect ??

Tom — Tue, 15 Oct 2013 03:40:02 GMT

I cannot see how entering the number as 22 (or really 0.22) could cause it to get that far off.

If you are storing the value in a permanent dataset make sure that the length of the variable is 8. On machines that use IEEE floating point (unix and windows) you can store numbers in as little as 3 bytes, but then SAS just throws away the rest of the bits used to represent the floating point number. If you try to store .22 into just 3 bytes when you read it back you get. 0.2199707031.

On an IBM mainframe you can even define a numeric variable as length 2, but even then it should not get as low as 0.21522222.

Re: Calculate Percentage incorrect ??

pcfriendly — Tue, 15 Oct 2013 03:44:52 GMT

OK, The length of the field is 8, the Type is Number & the Source Informat / Output Format / Output Informat are all PERCENT6.

Could the PERCENT6 be the problem?

Re: Calculate Percentage incorrect ??

pcfriendly — Tue, 15 Oct 2013 03:48:17 GMT

Thanks Tom,

I changed the PERCENT6 TO PERCENT8 & it now calculates correctly.

Many thanks !!