==== 维尔克松T检验(The Wilcoxon T test)====
对应于相关样本t检验,用于检验重复方差设计的两种处理条件之间的差异。
Corresponding to the correlation sample t test, and is used to test the difference between the two treatment conditions of the repeated variance design
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=== 维尔克松T检验的步骤 (Steps of Wilcoxon T test)===
== 1、确定虚无假设和备择假设 (Determine null hypothesis and alternative hypothesis)==
H0:不同处理间没有显著差异。(There is no significant difference among different treatments.)
H1:不同处理间有显著差异。(There are significant differences among different treatments.)
== 2、计算差异分数并排序 (Calculate the difference scores and rank them)==
计算每个样本不同处理下的分数差,此处差异分数的排序是按照差异分数绝对值的大小进行排序。
Calculate the score difference under different treatments for each sample, where the difference scores are sorted according to the magnitude of the absolute value of the difference scores.
== 3、计算正负差异分数的秩和 (Calculate the rank sum of positive and negative difference scores)==
排序后每个差异分数对应一个秩,分别计算正的差异分数的秩之和∑R+和负的差异分数的秩之和∑R-。
After sorting, each difference score corresponds to a rank. Then calculate the rank sum of the positive difference score ∑R+ and the rank sum of the negative difference score ∑R- respectively.
== 4、取T值并与临界T值比较 (Take the T-value and compare it with the critical T-value)==
T=min(∑R+,∑R-)
查表可以得到临界值Tcrit。
The criticle value Tcrit can be obtained by looking up the table.
若T<Tcrit,则拒绝H0。
If T<Tcrit, then reject H0.
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=== 大样本条件下的维尔克松T检验 ===
当n>25时,T分布近似服从正态分布。
该正态分布的均值为:
{{ ::t均值.jpg?nolink&150 |}}
方差为:
{{ ::t方差.jpg?nolink&200 |}}
由此可以将T分数标准化为z分数,查z分数表进行比较。
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=== 相同的等级和0分数 ===
在Wilcoxon 检验中,有两类相同的等级:
1、不同被试在不同处理条件下的差异分数相同;
2、同一个被试在不同处理条件下得到相同的分数,因此算出的差异分数为0。
**对于0分数,有两种做法:**
1、去掉差异分数为0的被试;
2、将0差异分数均匀地分配在正负两组中,即在计算正负差异分数的秩和时将0分数的秩平均分配于两组,这样将增大T值。