就這個(gè)數(shù)據(jù),前面的是個(gè)平均值,各有4-6份樣品,拿35個(gè)均值做正態(tài)性檢驗(yàn),就得出我提問之前那個(gè)圖,統(tǒng)計(jì)量為0.923
不好意思,我之前沒看清,你的0.923就是Shapiro-Wilks test的統(tǒng)計(jì)量,SPSS稱它為Shapiro-Wilk‘s W值,其對(duì)應(yīng)的P值就是依據(jù)0.923計(jì)算出來的。我查了SPSS幫助系統(tǒng),沒有說Shapiro-Wilk‘s W值服從正態(tài)分布(其他權(quán)威文獻(xiàn)也沒有說Shapiro-Wilk‘s W值服從正態(tài)分布),SPSS通過線性插值法在其模擬的臨界值范圍內(nèi)求出其P值(原文:Based on the computed W statistic, the significance is calculated by linearly interpolating within the range of simulated critical values given in Shapiro and Wilk (1965).)另一篇文獻(xiàn)這樣解釋:W may be thought of as the squared correlation coefficient between the ordered sample values (X') and the wi. The wi are approximately proportional to the normal scores Mi. W is a measure of the straightness of the normal probability plot, and small values indicate departures from normality.大致意思:W值是有序樣本(將樣本值從小到大排列,并計(jì)算其比例值)與對(duì)應(yīng)的正態(tài)分布比例值的相關(guān)系數(shù)的平方值,也就是對(duì)P-P圖的直線程度測(cè)量(若數(shù)據(jù)在P-P圖呈對(duì)角直線分布就符合正態(tài)分布),小的W值就表明背離正態(tài)分布。