Score transitions: P-type → D-type coding · Table S7 · Flokou et al., Healthcare 2025 · HLS19-VAC-GR
The HLS19-VAC-GR instrument uses 4 items, each rated on a 4-point scale (1 = Very Difficult … 4 = Very Easy). There are 4⁴ = 256 possible response patterns. Each pattern produces two scores:
P-type (polytomous): the mean of the 4 ratings, rescaled to 0–100. It has 13 distinct values (0, 8.3, 16.7 … 100).
D-type (dichotomous): responses 1–2 are recoded as 0 (difficult), responses 3–4 as 1 (easy); the percentage of "easy" responses gives a score with only 5 possible values (0, 25, 50, 75, 100).
Each cell shows how many patterns share a given P-type / D-type combination. Color reveals the direction of change caused by dichotomization: Higher the D-type score exceeds the P-type score · No change scores are equal · Lower the D-type score is below the P-type score.
By design, the Higher and Lower groups are perfectly symmetric (93 patterns each), while 70 patterns remain unchanged. This illustrates the information compression and many-to-one mapping induced by dichotomization — particularly relevant for HLS19-VAC-GR, which already shows a ceiling effect.
| P-type score |
D-type score | Row total |
||||
|---|---|---|---|---|---|---|
Click or tap any cell to highlight its row (P-type) and column (D-type) with a dot pattern. Use the filter buttons above to isolate one transition type. Hover or tap for details.