Table 3. Preference weights and relative importance of characteristics.
| Characteristics | Levels | Coef1 | SE2 | Z-score3 | p | Relative Importance 4 |
95% CI5 | |
|---|---|---|---|---|---|---|---|---|
| Chance of a false negative test result (the test result says people DO NOT HAVE the gene when people actually DO HAVE it)6 |
0 out of 10 times (0%) |
0.665 | 0.084 | 7.872 | 0.000 | 1.339 | 1.021 | 1.657 |
| 1 out of 10 times (10%) |
0.009 | 0.059 | 0.149 | 0.882 | ||||
| 2 out of 10 times (20%) |
−0.674 | 0.088 | −7.647 | 0.000 | ||||
| In addition to you, who else sees the test results |
Your primary care doctor |
0.978 | 0.092 | 10.576 | 0.000 | 2.639 | 2.240 | 3.038 |
| Your genetics health professionals |
0.684 | 0.083 | 8.190 | 0.000 | ||||
| Your life insurance and health insurance companies |
−1.661 | 0.124 | −13.393 | 0.000 | ||||
| Personal cost to you not covered by insurance |
$250 | 0.496 | 0.040 | 12.251 | 0.000 | 3.302 | 2.759 | 3.845 |
| $500 | −0.165 | 0.013 | −12.251 | 0.000 | ||||
| $1,000 | −1.486 | 0.121 | −12.251 | 0.000 | ||||
| $1,500 | −2.806 | 0.229 | −12.251 | 0.000 | ||||
| Genetic testing preference7 | Test | −1.643 | 0.145 | −11.336 | 0.000 | 1.643 | 1.357 | 1.929 |
| No test | −3.286 | 0.290 | −11.336 | 0.000 | ||||
Log odds (also termed preference weights) relative to the mean effect of the characteristic, which are normalized at zero using Z-scores to clearly distinguish where the differences occur between the log odds. The marginal log odds from the random-parameters logit model can be interpreted as weights indicating the relative strength of preference for each characteristic level. With this model, the relative changes between characteristic levels are the main focus. For example, the largest non-cost improvement in genetic testing features occurs between life insurance and health insurance companies and the primary care doctor as test result recipients.
Standard error
The Z-score is the coefficient divided by the standard error. Z-scores are used to identify statistically significant differences between attribute levels. Z-score ≥1.96 corresponds to a p-value≤0.05.
Relative importance represents the weight of each characteristic (over the levels of each characteristic included in the survey), which is estimated by taking the difference in the parameter estimates between the best and worst level for each attribute.
CI=Confidence Interval
Estimate for chance of a false negative was adjusted for the value of eliminating or reducing the risk of colorectal cancer shown in each choice question (i.e., 10%, 25%, or 50%)
Comparison of no testing to the alternative of the average test