| rank-difference correlation | The relationship between paired series of measurements, each ranked according to magnitude, which yields a coefficient known as rho; the value of rho varies from zero (no relationship) to +1.00 (perfect relationship). (05 Mar 2000) |
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| correlation | <statistics> most generally, the degree to which one phenomenon or random variable is associated with or can be predicted from another. In statistics, correlation usually refers to the degree to which a linear predictive relationship exists between random variables, as measured by a correlation coefficient. Correlation may be positive, i.e., both variables increase or decrease together or negative or inverse, i.e., one variable increases when the other decreases. (18 Nov 1997) |
| correlation coefficient | A measure of association that indicates the degree to which two variables have a linear relationship; this coefficient, represented by the letter r, can vary between +1 and -1; when r = +1, there is a perfect positive linear relationship in which one variable relates directly with the other; when r = -1, there is a perfect negative linear relationship between the variables. (05 Mar 2000) |
| product-moment correlation | A statistical procedure which yields the correlation coefficient referred to as r (-1.00 to +1.00) and involves the actual values, rather than the ranks (rank order) of the measurements. (05 Mar 2000) |
| absolute terminal innervation ratio | The number of motor endplates divided by the number of terminal axons related to them. (05 Mar 2000) |
| accommodative convergence-accommodation ratio | The amount of convergence (measured in prism diopters of convergence) divided by the amount of accommodation (measured in diopters) required to direct both eyes upon an object. (05 Mar 2000) |
| A/G ratio | <abbreviation> Albumin-globulin ratio. (05 Mar 2000) |
| albumin-globulin ratio | The ratio of albumin to globulin in the serum or in the urine in kidney disease; the normal ratio in the serum is approximately 1.55. (05 Mar 2000) |
| ALT:AST ratio | The ratio of serum alanine aminotransferase to serum aspartate aminotransferase; elevated serum levels of both enzymes characterise hepatic disease; when both levels are abnormally elevated and the ALT:AST ratio is greater than 1.0, severe hepatic necrosis or alcoholic hepatic disease is likely; when the ratio is less than 1.0, an acute non-alcoholic hepatic condition is favoured. (05 Mar 2000) |
| amylase-creatinine clearance ratio | A test for the diagnosis of acute pancreatitis; it is determined by measuring amylase and creatinine in serum and urine in apparently healthy individuals the renal clearance of amylase is less than 5% that of creatinine; in acute pancreatitis the ratio is said to be greater than 0.05 or 5%. (05 Mar 2000) |
| aspect ratio | <radiobiology> In toroidal geometry, the ratio of the major diameter (total width of the torus) to the minor diameter (width of a slice taken through one side of the ring). In inertial-confinement fusion, aspect ratio refers to the ratio of a fuel pellet's radius to its wall thickness. (09 Oct 1997) |
| at/gc ratio | <molecular biology> The ratio of adenine-thymine base pairs to guanine-cytosine base pairs on a DNA molecule. (09 Oct 1997) |
| basic reproductive rate, ratio | <epidemiology> See Reproductive Ratio. (05 Dec 1998) |
| body-weight ratio | Body weight (in grams) divided by stature (in centimeters). (05 Mar 2000) |
| branching ratio | <radiobiology> In a fusion reaction involving two nuclei, there are typically a variety of possible sets of products which can form. The branching ratio for a particular set of products is the probability that that set of products will be produced. (09 Oct 1997) |