application or intradermal injection of a substance to the skin to test the body's reaction to it. Such a test detects an animal's sensitivity to such allergens as dust and pollen, or to preparations of microorganisms believed to be the cause of a disorder.
A direct relationship graph is a graph where one variable either increases or decreases along with the other. The general equation for a direct relationship graph is y = mx + b, where y denotes the...
When surveys and naturalistic observations reveal that one trait or behavior accompanies another, we say the two correlate. A correlation coefficient is a statistical measure of relationship. A posi- tive correlation indicates a direct relationship, meaning that two things increase together or decrease together. A negative correlation indicates an inverse relationship: As one thing increases, the other decreases, and vice versa.