Table 3.
Test-retest reproducibility of food groups for the food-frequency questionnaire (n = 21)
| FFQ 1 | FFQ 2 | Spearman’s r | P | CC % | GM % | Kappa k | P | |||
|---|---|---|---|---|---|---|---|---|---|---|
| Median | (P25, P75) | Median | (P25, P75) | |||||||
| Milk, yoghurt, milk dessert (ml/day) | 184 | (103, 335) | 168 | (54, 266) | 0.81 | < 0.001 | 62 | 0 | 0.43 | 0.006 |
| Cheese (g/day) | 20 | (10, 31) | 18 | (2.9, 35) | 0.82 | < 0.001 | 67 | 0 | 0.50 | 0.001 |
| Eggs (g/day) | 18 | (16, 54) | 18 | (12, 66) | 0.90 | < 0.001 | 67 | 0 | 0.51 | < 0.001 |
| Poultry (g/day) | 22 | (11, 54) | 21 | (11, 31) | 0.76 | < 0.001 | 71 | 5 | 0.57 | < 0.001 |
| Red meat, non-processed (g/day) | 12 | (10, 20) | 20 | (8.5, 28) | 0.85 | < 0.001 | 62 | 0 | 0.43 | 0.005 |
| Red meat, processed (g/day) | 14 | (1.8, 19) | 9.3 | (1.8, 21) | 0.22 | 0.331 | 33 | 14 | 0.01 | 0.946 |
| Liver-pate (g/day) | 0 | (0, 7.1) | 2.9 | (0, 7.1) | 0.69 | 0.001 | 71 | 10 | 0.54 | 0.001 |
| Meat dishes (g/day) | 45 | (23, 66) | 45 | (21, 67) | 0.66 | 0.001 | 52 | 5 | 0.29 | 0.063 |
| Fatty fish (g/day) | 11 | (5.4, 21) | 11 | (11, 21) | 0.40 | 0.073 | 71 | 10 | 0.56 | < 0.001 |
| Lean fish (g/day) | 14 | (0, 29) | 14 | (0, 14) | 0.79 | < 0.001 | 71 | 0 | 0.56 | < 0.001 |
| Fish spread (g/day) | 7.9 | (0, 14) | 5.7 | (0, 22) | 0.70 | < 0.001 | 71 | 5 | 0.57 | < 0.001 |
| Fish dishes (g/day) | 11 | (0, 11) | 11 | (0, 11) | 0.46 | 0.035 | 43 | 14 | 0.23 | 0.033 |
| Breakfast cereal, high grain (g/day) | 14 | (7.1, 107) | 36 | (7.1, 100) | 0.83 | < 0.001 | 71 | 0 | 0.57 | < 0.001 |
| Rice, pasta, noodle (g/day) | 76 | (46, 113) | 76 | (43, 133) | 0.55 | 0.010 | 52 | 10 | 0.28 | 0.066 |
| Bread, crispbread, low fibre (g/day) | 5.7 | (0, 17) | 5.7 | (0, 23) | 0.75 | < 0.001 | 86 | 5 | 0.78 | < 0.001 |
| Bread, crispbread, high fibre (g/day) | 102 | (34, 142) | 102 | (38, 123) | 0.76 | < 0.001 | 71 | 5 | 0.57 | < 0.001 |
| Nuts, almonds (g/day) | 1.4 | (0.7, 7.1) | 2.9 | (0.7, 7.1) | 0.64 | 0.002 | 71 | 5 | 0.56 | < 0.001 |
| Potatoes (g/day) | 33 | (20, 68) | 31 | (15, 72) | 0.76 | < 0.001 | 62 | 5 | 0.43 | 0.006 |
| Vegetables (g/day) | 116 | (75, 189) | 102 | (69, 163) | 0.84 | < 0.001 | 71 | 5 | 0.57 | < 0.001 |
| Fruits (g/day) | 172 | (50, 249) | 133 | (58, 304) | 0.76 | < 0.001 | 67 | 0 | 0.50 | 0.001 |
| Sugar, sweets, desserts(g/day) | 28 | (12, 37) | 25 | (12, 39) | 0.70 | < 0.001 | 57 | 5 | 0.36 | 0.020 |
| Oils, butter, margarine (g/day) | 2.1 | (0.4, 16) | 2.9 | (0, 10) | 0.93 | < 0.001 | 81 | 0 | 0.71 | < 0.001 |
| Coffee, tea, water (ml/day) | 964 | (789, 1323) | 964 | (735, 1196) | 0.90 | < 0.001 | 76 | 0 | 0.64 | < 0.001 |
| Juice, sweet drinks (ml/day) | 171 | (111, 257) | 200 | (86, 489) | 0.72 | < 0.001 | 52 | 0 | 0.29 | 0.060 |
| Alcohol (ml/day) | 53 | (1.4, 154) | 69 | (19, 111) | 0.83 | < 0.001 | 81 | 5 | 0.72 | < 0.001 |
| Pizza (g/day) | 43 | (21, 43) | 21 | (21, 43) | 0.38 | 0.088 | 33 | 5 | 0.16 | 0.038 |
| Salty snacks (g/day) | 5.7 | (2.9, 8.6) | 5.7 | (2.9, 8.6) | 0.58 | 0.006 | 48 | 10 | 0.21 | 0.156 |
| Mixed dishes (g/day) | 84 | (79, 173) | 84 | (70, 154) | 0.75 | < 0.001 | 67 | 5 | 0.49 | 0.001 |
Food intake (gram/milliliter per day) for food groups (median, 25th and 75th percentile, Spearman’s rank correlation coefficient, percent correctly classified (CC) and grossly misclassified (GM) into tertiles of intake, Cohen’s Kappa value). Statistically significant p-values marked in bold