Table 2.
Item analyses for each item in the online salt knowledge questionnaire
| Category | Section/question | DI | IDI | ITC |
|---|---|---|---|---|
| Declarative knowledge | Dietary recommendations | |||
| Which of the following statements best describes the relationship between salt and sodium? (salt contains sodium)† | 0·5 | 0·7 | 0·422 | |
| How many grams of salt is equivalent to one teaspoon of salt? (4 g) | 0·6 | 0·5 | 0·387 | |
| A product is considered as ‘low in salt’ when it contains… (120/100 mg) | 0·9 | 0·5 | 0·643 | |
| What is the maximum recommended daily amount of salt for an adult in Australia? (6 g)‡ | 0·3 | 0·2 | 0·269 | |
| Conditions which might be associated with high salt intakes | ||||
| High blood pressure‡ | 0·0 | 1·0 | – | |
| High blood sugar | 0·4 | 0·7 | 0·320 | |
| Stroke‡ | 0·0 | 1·0 | 0·000 | |
| Kidney disease‡ | 0·1 | 0·9 | 0·095 | |
| Osteoporosis | 0·5 | 0·4 | 0·391 | |
| Salt content of commonly eaten foods | ||||
| White bread (medium)‡ | −0·1 | 0·5 | −0·087 | |
| Bacon (high)‡ | 0·2 | 0·9 | 0·337 | |
| White rice (boiled) (low) | 0·6 | 0·8 | 0·425 | |
| Beef steak (uncooked) (low) | 0·5 | 0·7 | 0·357 | |
| Mix vegetables (frozen) (low) | 0·5 | 0·8 | 0·420 | |
| Corn flakes (medium)‡ | −0·1 | 0·4 | −0·075 | |
| Vegemite (high) | 0·3 | 0·8 | 0·325 | |
| Cheddar cheese (processed) (high) | 0·4 | 0·8 | 0·430 | |
| Salt is naturally present in fresh food‡,§ | 0·2 | 0·7 | 0·139 | |
| Fast foods are high in salt‡,§ | 0·0 | 1·0 | 0·150 | |
| Bread is one of the main sources of salt in Australians’ diets§ | 0·5 | 0·6 | 0·435 | |
| Common misconceptions | ||||
| Sea salt is better than table salt∥,§ | 0·7 | 0·6 | 0·554 | |
| Drinking more water can neutralise salt in my diet∥,§ | 0·4 | 0·8 | 0·434 | |
| Cutting down on salt causes leg cramps∥,§ | 0·5 | 0·8 | 0·388 | |
| Procedural knowledge | Label reading | |||
| Which pasta sauce has the highest salt content‡ | 0·2 | 0·9 | 0·192 | |
| If you see a TICK logo on a packet of breakfast cereal, what do you think about the product? | 0·5 | 0·8 | 0·447 |
DI, discrimination index; IDI, item difficulty index; ITC, item-to-total correlation.
†Correct answers are in parentheses after each item.
‡Items which were retained for the purpose of content validity.
§Indicates items were scored as: 2 = ‘certainly true’, 1 = ‘probably true’, 0 = all others; otherwise items were scored as 1 = correct answer; 0 = all others. Negative statements were reversed prior to scoring.
∥Items were reversed coded prior to scoring.