R-value
Encyclopedia
R-value can refer to:
- Properties of materials:
- R-value (insulation)R-value (insulation)The R-value is a measure of thermal resistance used in the building and construction industry. Under uniform conditions it is the ratio of the temperature difference across an insulator and the heat flux through it or R = \Delta T/\dot Q_A.The R-value being discussed is the unit thermal resistance...
, the efficiency of insulation of a house - R-value (soils)R-value (soils)The R-Value test, , measures the response of a compacted sample of soil or aggregate to a vertically applied pressure under specific conditions. This test is used by Caltrans for pavement design, replacing the California bearing ratio test...
, stability of soils and aggregates for pavement construction
- R-value (insulation)
- r-valueValue (computer science)In computer science, a value is an expression which cannot be evaluated any further . The members of a type are the values of that type. For example, the expression "1 + 2" is not a value as it can be reduced to the expression "3"...
, in computer science, a value that does not have an address in a computer language - R-factor (crystallography)R-factor (crystallography)In crystallography, the R-factor is a measure of the agreement between the crystallographic model and the experimental X-ray diffraction data. In other words, it is a measure of how well the refined structure predicts the observed data...
, a measure of the agreement between the crystallographic model and the diffraction data - In statistics, r (or r value) refers to the Pearson product-moment correlation coefficientPearson product-moment correlation coefficientIn statistics, the Pearson product-moment correlation coefficient is a measure of the correlation between two variables X and Y, giving a value between +1 and −1 inclusive...
, often called simply correlation coefficient - In ophthalmic optics, r-value refers to the distance between the segment optical center and the segment top