**F-ratio** — In oceanic biogeochemistry, the f ratio is the fraction of total primary production fuelled by nitrate (as opposed to that fuelled by other nitrogen compounds such as ammonium). This fraction is significant because it is assumed to be directly… … Wikipedia

**f ratio** — or f number or f stop (f/ or f) a measure of the light gathering power of the lenses in cameras and telescopes. The f ratio, for example f/4 or f4, is the aperture of the lens (the effective diameter of the lens, which may be reduced or… … Dictionary of units of measurement

**F-ratio** — the variance between the means of several groups relative to the variance within the groups; used in the F test (q.v.) in the analysis of variance (ANOVA) … Medical dictionary

**F-ratio (disambiguation)** — F ratio or f ratio may refer to:* f number, f ratio, or focal ratio, the ratio of the focal length of an optical system to the diameter of its entrance pupil; * f ratio, in oceanography, which relates recycled and total primary production in the… … Wikipedia

**F-ratio test** — [Sir Ronald Aylmer Fisher, British statistician, 1890â€“1962] see under ratio and test … Medical dictionary

**A/F ratio** — See air fuel ratio … Dictionary of automotive terms

**F-number** — In optics, the f number (sometimes called focal ratio, f ratio, or relative aperture [Smith, Warren Modern Lens Design 2005 McGraw Hill] ) of an optical system expresses the diameter of the entrance pupil in terms of the focal length of the lens; … Wikipedia

**ratio** — A fixed relationship between things in number, quantity or degree. For example, if the fuel mixture contains one part of gas for fifteen parts of air, the ratio would be 15 to 1. See a/f ratio a/f ratio air fuel ratio air fuel ratio air ratio… … Dictionary of automotive terms

**F-test** — An F test is any statistical test in which the test statistic has an F distribution if the null hypothesis is true. The name was coined by George W. Snedecor, in honour of Sir Ronald A. Fisher. Fisher initially developed the statistic as the… … Wikipedia

**F-test** — a statistical test comparing the means of more than two groups simultaneously by comparing two different measures of variance of the observations. One statistic measures the variations between the means of the groups (the between groups… … Medical dictionary