The Juster Scale is a verbal probability scale designed to estimate future behaviour. It was developed by FT Juster in 1966 and appears in the academic literature fairly often. However, it does not seem to be used very often by European MR agencies. It appears to be more suitable for product category purchase, as opposed to specific brand purchase – this may explain why it is less popular with agencies.

The main criticism of the Juster scale is that it tends to over-predict share, something which might be reduced by re-scaling or by using just the top-end of the scale. For example the 0-10 scale is sometimes squared and the results used as percents (10→100%, 9→81%, 8→64%,….., 2→4%, 1→1%, 0→0%).

Consideringthe published papers, the Juster scale appears to be cited much more often in Australia and New Zealand, compared with other markets. A paper was presented to the 1999 MRSA Annual Conference (note MRSA is now AMSRS) which looked at the adoption in Australia of the Bass Model, and used the Juster scale as a comparator.

The standard Juster scale is an 11 point scale, like the one shown below.

10 Certain, practically certain (99 in 100)
9 Almost sure (9 in 10)
8 Very probable (8 in 10)
7 Probable (7 in 10)
6 Good possibility (6 in 10)
5 Fairly good possibility (5 in 10)
4 Fair possibility (4 in 10)
3 Some possibility (3 in 10)
2 Slight possibility (2 in 10)
1 Very slight possibility (1 in 10)
0 No chance, almost no chance (1 in 100)

Dianne, Gan, Gendall, Esslemont produced a very good summary of the Juster scale in an article in the New Zealand Marketing Bulletin in 1991. They also reported on two experiments they had carried out in New Zealand. A paper that links the Juster scale with the context of tourism in Australia was presented in Canberra at this year’s CAUTH conference. The paper by Ryan and Huyton, used the Juster scale to help estimate drivers of choice. References Juster, F T (1966). Consumer buying intentions and purchase probability. Occasional Paper 99, National Bureau of Economic Research, Colombia University Press.

Juster, F T (1969). Consumer anticipations and models of durable goods demand. In Mincer, J (1969). Economic Forecasts and Expectations. National Bureau of Economic Research.

Dianne Day, Boon Gan, Philip Gendall and Don Esslemont (1991). Predicting Purchase Behaviour, Marketing Bulletin (NZ), 1991, Volume 2

Chris Ryan, Jeremy Huyton (2001). Balanda Visitors to Central Australia: Their Perceptions, 2001 CAUTHE National Research Conference, Canberra