Goal Attainment Scaling:
The Math!

Below you will see a GAS assessment for the fictitious client -- Philip. To understand how the scales were developed, you are invited to read Philip’s social history (found by clicking). The numbers in the cell in the BOLD font indicate Philip’s level of attainment for that particular session. Thus, under “Alcoholism,” the practitioner assessed Philip to be “much less than expected outcome” for the first four (4) sessions. During the 5^th and 6^th session, the practitioner assessed Philip to be “less than expected outcome.” At the 7^th and final session, Philip was assessed at the “expected outcome.” On the second scale “Homosexuality,” the practitioner assessed Philip at “much less than expected outcome” for the first two sessions.

Levels of  Predicted  Attainment	Alcoholism wt (9)	Homosexuality wt (10)	Job Performance wt (7)	Paranoia wt (4)
-2 Much less than expected  outcome	Uncontrollable desire to drink 1   2   3   4 5   6  7	Will not consider exposing to wife 1 2   3   4  5  6   7	Has poor job performance 1 2 3   4  5  6   7	Feeling that everyone is against him 1   2  3  4  5  6   7
-1 Less  than  expected outcome	Has control some of the time 1  2  3  4 5   6 7	1  2  3   4   5   6   7	Shows small amount of job performance improvement 1   2 3   4   5 6   7	Able to control paranoia feelings 1   2   3 4 5 6   7
0 Expected  outcome	Continues to have desires, but is able to control most of the time 1   2   3   4   5   6   7	Considers but is not willing to expose 1  2 3  4  5  6 7	Maintain job with adequate evaluations 1 2   3   4   5   6   7	Feeling comfortable with his paranoia 1   2   3   4   5 6 7
+1 More than  expected  outcome	1   2   3   4   5   6   7	Willing to do role playing 1   2   3   4   5   6   7	Job evaluations show improvement 1   2   3   4   5 6   7	Functions with little feelings of paranoia 1   2   3   4   5   6 7
+2 Much  more than  expected  outcome	Able to control desire to drink 1   2   3   4   5   6   7	Willing to discuss with wife 1   2   3   4   5  6 7	Excellent job performance evaluations 1   2   3   4   5   6   7	Shows no paranoia 1   2   3   4   5   6   7

To begin, one needs to calculate the results for each individual session. We begin with session 1 by multiplying the level of attainment by the weight then sum all the quotients:

Alcoholism (session 1)
- 2	X	9	=	-18
Homosexuality (session 1)
- 1	X	10	=	-10
Job Performance (session 1)
- 0	X	7	=	0
Paranoia (session 1)
- 2	X	4	=	-8
			Total	-36

The GAS composite score for the first session equals -36. This number (-36) is place below the GAS graphic as seen below.

The GAS composite scores can be graphed. The graphic gives evaluators a quick assessment of the process of all the clients being serviced.

GAS Composite Scores
1 = -36	2 = __	3 = __	4 = __	5 = __	6 = __	7 = __