Table 1.
VIF and Type-I Error Control in the presence of a confounder
| VIF Estimate | Type-I Error | |||||
|---|---|---|---|---|---|---|
| Sample Size | Percent Conf. | True VIF | QuSAGE | Q-Gen | Qusage | Q-Gen |
| 5 | 0 | 20.024 | 19.04 | 18.89 | .046 | .054 |
| 5 | .25 | 20.024 | 17.43 | 18.87 | .042 | .050 |
| 5 | .5 | 20.024 | 17.89 | 18.89 | .041 | .055 |
| 5 | 0 | 6.435 | 6.20 | 6.16 | .044 | .050 |
| 5 | .25 | 6.435 | 6.282 | 6.2 | .040 | .054 |
| 5 | .5 | 6.435 | 8.04 | 6.16 | .045 | .055 |
| 5 | 0 | 1 | 0.99 | 0.99 | .048 | .053 |
| 5 | .25 | 1 | 1.72 | 1.00 | .041 | .054 |
| 5 | .5 | 1 | 4.16 | 0.99 | .010 | .057 |
| 15 | 0 | 20.024 | 19.75 | 19.74 | .047 | .047 |
| 15 | .25 | 20.024 | 18.72 | 19.72 | .056 | .049 |
| 15 | .5 | 20.024 | 18.59 | 19.71 | .0822 | .053 |
| 15 | 0 | 6.435 | 6.36 | 6.36 | .053 | .052 |
| 15 | .25 | 6.435 | 6.43 | 6.36 | .072 | .052 |
| 15 | .5 | 6.435 | 8.27 | 6.34 | .101 | .051 |
| 15 | 0 | 1 | 1.00 | 1.00 | .048 | .049 |
| 15 | .25 | 1 | 1.719 | 1.00 | .097 | .050 |
| 15 | .5 | 1 | 4.176 | 1.00 | .074 | .051 |
VIF and type-I error estimates under a case-control simulation in the presence of a confounding variable where the percentage of genes that are affected by the confounder are examined for 0, 25, and 50 % respectively. Error rates in bold indicate they are within the margin of error (0.05 ± 0.00427) for the simulation study. Since Q-Gen allows for a linear model that adjusts for covariates, VIF estimation and the controlling of the type-I error is more consistent than the standard two sample t-testing conducted within QuSAGE