Many experts were consulted to decide which quantitative risk
factors to use in calculating this Health Risk Appraisal. To be included a risk factor had to:
1. Be conclusively shown to be important.
2. Have data showing its numeric effect on the disease.
3. Be something people can answer questions about.
For example, Human Papilloma Virus (one of the viruses which cause warts) on a previous pap smear has conclusively been (1) shown to be important, (2) its risk can be quantitated, but (3) most women don't know if its ever been seen on one of their pap smears so it was not used.