Table 3.
Classical and Item Response Theory Results for the Lipkus Expanded Numeracy Scale
| A. Full Lipkus | B. Modified Lipkus | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Item | % Correct |
Item-Subscale Correlation |
IRT Discrimination |
IRT Difficulty |
Chi- Square |
df | p | Item-Subscale Correlation |
IRT Discrimination |
IRT Difficulty |
| 1 | 0.69 | 0.60 | 1.57 | −0.68 | 24.70 | 7 | < 0.01 | .49 | 1.69 | −0.70 |
| 2 | 0.54 | 0.57 | 1.48 | −0.13 | 7.57 | 6 | 0.28 | .49 | 1.58 | −0.16 |
| 3 | 0.18 | 0.51 | 2.42 | 1.16 | 0.68 | 2 | 0.70 | .43 | 3.59 | 1.03 |
| 4 | 0.88 | 0.45 | 1.44 | −1.75 | 8.44 | 7 | 0.35 | .35 | 1.31 | −1.92 |
| 5 | 0.89 | 0.39 | 1.32 | −1.94 | 14.50 | 7 | < 0.05 | .28 | 1.05 | −2.35 |
| 6 | 0.84 | 0.55 | 1.69 | −1.36 | 9.87 | 7 | 0.27 | .43 | 2.58 | −1.21 |
| 7 | 0.80 | 0.65 | 1.92 | −1.06 | 6.30 | 6 | 0.40 | .52 | 3.31 | −0.95 |
| 8 | 0.84 | 0.55 | 12.92 | −0.95 | 728.00 | 2 | < 0.01 | -- | -- | -- |
| 9 | 0.79 | 0.58 | 6.08 | −0.80 | 240.00 | 3 | < 0.01 | -- | -- | -- |
| 10 | 0.68 | 0.58 | 1.68 | −0.63 | 13.50 | 7 | 0.08 | .48 | 1.53 | −0.70 |
| 11 | 0.41 | 0.60 | 1.66 | 0.35 | 9.73 | 5 | 0.09 | .47 | 1.56 | 0.33 |