所谓Expected value，参考http://www.ats.ucla.edu/stat/Spss/whatstat/whatstat.htm

并比较其与http://www.psych.northwestern.edu/Misc/spss/chi.htm中的问题和方法，就应该清楚了

认真回顾一下chi-square distribution和 chi-square test的本质，将有助理解上面内容

By default, all categories have equal expected values. Categories can have user-specified expected proportions. Select Values, enter a value greater than 0 for each category of the test variable, and click Add. Each time you add a value, it appears at the bottom of the value list. The order of the values is important; it corresponds to the ascending order of the category values of the test variable. The first value of the list corresponds to the lowest group value of the test variable, and the last value corresponds to the highest value. Elements of the value list are summed, and then each value is divided by this sum to calculate the proportion of cases expected in the corresponding category. For example, a value list of 3, 4, 5, 4 specifies expected proportions of 3/16, 4/16, 5/16, and 4/16.