| How much difficulty do you have driving in the dark? In the rain? In the mist? |
Binning – Binned together, ie, How much difficulty do you have driving in poor visibility (in the dark, mist or rain)? |
| How often do you experience misty vision? Cloudy vision? Hazy vision? Vision as if you are looking through a veil? |
Winnowing – Kept the most representative item (ie, experiencing cloudy vision), removed the other items. |
| How often do you feel hopeful? How often do you feel hopeless? |
Winnowing – Removed all positively-phrased emotional concepts (eg, hopeful) and kept negative counterpart (eg, hopeless). |
| How much trouble is not doing everything you want to do? |
Removed – Item was unclear and too general. |
| How much difficulty do you have reading the menu in a dimly lit restaurant? |
Removed – Item was too specific. |
| How often do you experience stinging pain in your eye? |
Removed – Item was similar to another item (ie, How often do you experience stinging in your eye?). |
