Table 2 Correlation coefficients between variables in ‘wine quality_red’ data set
Fixed.acidity | Volatile.acidity | Citric.acid | Residual.sugar | Chlorides | Free.sulfur.dioxide | Total.sulfur.dioxide | Density | pH | Sulphates | Alcohol | Quality | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Fixed.acidity | 1 | – | – | – | – | – | – | – | – | – | – | – |
Volatile.acidity | − 0.2561 | 1 | – | – | – | – | – | – | – | – | – | – |
Citric.acid | 0.6717 | − 0.5525 | 1 | – | – | – | – | – | – | – | – | – |
Residual.sugar | 0.1148 | 0.0019 | 0.1436 | 1 | – | – | – | – | – | – | – | – |
Chlorides | 0.0937 | 0.0613 | 0.2038 | 0.0556 | 1 | – | – | – | – | – | – | – |
Free.sulfur.dioxide | − 0.1538 | − 0.0105 | − 0.061 | 0.187 | 0.0056 | 1 | – | – | – | – | – | – |
Total.sulfur.dioxide | − 0.1132 | 0.0765 | 0.0355 | 0.203 | 0.0474 | 0.6677 | 1 | – | – | – | – | – |
Density | 0.668 | 0.022 | 0.3649 | 0.3553 | 0.2006 | − 0.0219 | 0.0713 | 1 | – | – | – | – |
pH | − 0.683 | 0.2349 | − 0.5419 | − 0.0857 | − 0.265 | 0.0704 | − 0.0665 | − 0.3417 | 1 | – | – | – |
Sulphates | 0.183 | − 0.261 | 0.9128 | 0.0055 | 0.3713 | − 0.0517 | 0.0429 | 0.1485 | − 0.1966 | 1 | – | – |
Alcohol | − 0.0617 | − 0.2023 | 0.1099 | 0.0421 | − 0.2211 | − 0.0694 | − 0.2057 | − 0.4962 | 0.2056 | 0.0936 | 1 | – |
Quality | 0.1241 | − 0.3906 | 0.2264 | 0.0137 | − 0.1289 | − 0.0507 | − 0.1851 | − 0.1749 | − 0.0577 | 0.2514 | 0.4762 | 1 |