Fig. 1

Multi-trait correlation matrix for 29 ATAQ-LAM items that form the Exertional Dyspnea, Cough, Fatigue and Emotional Well-Being subscales. Footnote: ExD=exertional dyspnea domain; each row is an item, and each column is a domain; values are correlations between an item and each of the four domains; white=items hypothesized to belong to the domain indicated by its column header; perfect scaling for an item would be indicated by a row with three green rectangles and one white rectangle that contains an asterisked value; *=correlation in white is significantly stronger than correlations in same row marked green (scaling success); yellow=probable scaling success—correlation coefficient in white is greater than correlation coefficient in yellow, but the difference did not reach statistical significance; orange=possible scaling success—correlation coefficient in white is lesser than correlation coefficient in orange, but the difference did not reach statistical significance