A-level Mathematics/OCR/S1/Bivariate Data

Bivariate data

SYLABUS EXTRACT:

(a) calculate, both from simple raw data and from summarised data, the product moment correlation coefficient for a set of bivariate data; (b) understand the basis of Spearman’s coefficient of rank correlation, and calculate its value (questions set will not involve tied ranks); (c) interpret the value of a product moment correlation coefficient or of Spearman’s rank correlation coefficient in relation to the appearance of a scatter diagram, with particular reference to values close to 1, − 0,1; (d) understand that the value of a correlation coefficient is unaffected by linear transformations (coding) of the variables; (e) understand the difference between an independent (or controlled) variable and a dependent variable; (f) understand the concepts of least squares and regression lines in the context of a scatter diagram; (g) calculate, both from simple raw data and from summarised data, the equation of a regression line, understand the distinction between the regression line of y on x and that of x on y, and use the fact that both regression lines pass through the mean centre (x, y); (h) select and use, in the context of a problem, the appropriate regression line to estimate a value, and be able to interpret in context the uncertainties of such estimations.