Also known as the Pearson product-moment correlation coefficient, the correlation coefficient (r) measures the linear relationship between two variables, with a value range of -1 to 1. A value close to 1 indicates there is a strong positive linear correlation between two variables; that is, when one variable increases so does the other.
A short definition. Delta H of a reaction is the enthalpy of reaction. H of products minus H of reactants. Each compound has a delta H of formation (dHf). The heats of formation for each substance in a reaction can be added together to compute the energy change for a reaction.
For color samples in saturated areas, a delta E of 1 is not normally visible to an untrained eye. However, the color cast can be detected between two colors close to the gray axis. The absolute color difference between two sample s is known as the hue difference (delta h*). This measured value is used to calculate the frac tional value of delta E, which evolves from the hue difference between two color samples alone. Differences in brightness are ignored during the calculation of delta H.