相关系数种类（Types of correlation coefficients）Types of correlation coefficients(I) Pearson product difference correlation (K. Pearson product-moment correlation; R)1. X variables: isometry, ratio variables (continuous variables)2. Y variables: isometry, ratio variables (continuous variables)3. formula:4. characteristics: numerical stability, standard error.5. cases: the relationship between working hours and income.(two) Spearman rank correlation (Spearman rank correlation; RS)1. X variables: ordinal variables2. Y variables: ordinal variables3. formula:(1) without the same rank: (D is the rank difference of two variable symmetry)(2) people with the same grade:T: the number of people who receive the same grade.4. features: suitable for two raters to evaluate N pieces, or the same rater, two times to evaluate N pieces.5. cases: evaluation of N students works by two reviewers.(three) Kendall rank correlation (Kendalls coefficient of rank correlation; (tau)1. X variables: human order variables2. Y variables: human order variables3. formula: S: rank ordinal quantity; N: the number of persons evaluated or the number of works4. features: quite simple5. cases: evaluation of N students works by two reviewers.(four) Kendall concordance coefficient (the Kendalls coefficient of concordance; W)1. X variables: ordinal variables2. Y variables: ordinal variables3. formula:(1) without the same grade:;(2) people with the same grade:;K: the number of raters; N: the number of persons being evaluated or the number of entries4. features: especially for the inter rater reliability (interjudge reliability); test the consistency of the evaluation of N works by many reviewers.5. cases: evaluation of N students works by multi site evaluation.(five) Kappa consistency coefficient (K coefficient of agreement; K)1. X variables: categorical variables2. Y variables: categorical variablesThe 3. formula: the Kappa consistency coefficient is the ratio of the percentage of the actual evaluation of the raters to the percentage of the maximum possible number of raters evaluated by the raters (Lin Wei, 1992). Formula for:P (A): the percentage of K rater ratings;N: total number; K: rater number; m: rating category; N: fine grid dataP (E): K score raters can theoretically assess the percentage of consistency; when the raters rating is exactly the same, then K=1, when the raters rating is completely inconsistent, then K=0.； ；4. characteristics: the Kendeer harmony coefficient, the score is limited in the evaluation object can be evaluated. That is, can list the order. However, in some cases cannot be assessed object list rank order, and can only be classified in a category, at this time, you must use Kappa to indicate the consistency coefficient, the consistency of the relationship between the score.5. cases: K psychiatrists, N patients were classified into m categories of mental illness after diagnosis.(six) two series correlation (biserial correlation; RBIs)1. X variables: anthropogenic two variables (nominal variables)2. Y variables: continuous variables (isometric, ratio variables)3. formula:4. features: use in project analysis; standard error is large; RBIs may be greater than 1.5. cases: the relationship between IQ and academic achievement or not.(seven) point two series correlation (point-biserial correlation; rpq)1. X variables: real two variables (nominal variables)2. Y variables: continuous variables3. formula:Table 1: the average of the first class; the mean of the first class; St: the standard deviation of the total fraction;P: Table 1 percentage of the number of people; Q: percentage of people in table second.4. characteristic: standard error is smaller than rbis.5. cases: the relationship between gender (male, female) and income.(eight) correlation (phi coefficient;)1. X variables: real two variables (nominal variables)2. Y variables: real two variables (nominal variables)ABCD3. formula:4. characteristics: closely related to Chi square test.5. cases: parental parenting style (authoritative, democratic).(nine) contingency correlation (contingency coefficient; C)1. X variables: real two or more nominal variables2. Y variables: real two or more nominal variables3. formula: the maximum value of C is N, and the total number is4. characteristics: closely related to Chi square test.5. cases: the attitude of the people (teachers and students) towards the implementation of the policy (agreement, no opinion, no agreement).(ten) four point correlation (tetrachoric correlation; TET)1. X variables: human two nominal variables (raw data are equidistant variables)2. Y variables: human two nominal variables (raw data are equidistant variables)ABC