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.
The E in Delta E comes from the German word Empfindung, meaning feeling, sensation. Delta comes from the Greek language, and is used in mathematics (as the symbol Î) to signify an incremental change in a variable, i.e., a difference. So, Delta E comes to mean a difference in sensation. A Delta E of 1 between two colors that are not touching one another is is generally considered to be barely perceptible by the average human observer; a Delta E between 3 and 6 is typically considered an acceptable match in commercial reproduction on printing presses. (Note: Human vision is more sensitive to color differences if two colors actually touch each other.) The higher the Delta E, the greater the difference between the two ...