拉丁方实验设计

具体的说拉丁方是一种为减少实验顺序对实验的影响,而采取的一种平衡实验顺序的技术。采用的是一种拉丁方格做辅助,拉丁方格就是由需要排序的几个变量构成的正方形矩阵。其具体的应用过程是这样的:
当处理数是偶数,其顺序是这样确定的,横排:1,2,n,3,n-1,4,n-2……(n代表要排序的量的个数),随后的次序是在第一个次序的数目上加“1”,直到形成拉丁方。
假设处理数是6,则拉丁方如下:
A B F C E D
B C A D F E
C D B E A F
D E C F B A
E F D A C B
F A E B D C

拉丁方以表格的形式被概念化,其中行和列代表两个外部变量中的区组,然后将自变量的级别分配到表中各单元中。简单的说就是某一变量在其所处的任意行或任意列中,只出现一次。


2 Experimental Methods

•It is important to select the right experimental method so that the results of the experiment can be generalized

•There are mainly two experimental methods

between-groups:

 each subject is assigned to one experimental condition

– Each subject performs under all the different conditions

 – Repeated-measure

within-groups

each subject performs under all 

the different conditions

– Each subject is assigned to one experimental condition

《拉丁方实验设计》 
《拉丁方实验设计》


Within-subjectsBetween-subjects 
Learning effectAvoids interference effects
(e.g. practice / learning effect)
 
Longer time for each participant
(larger impact of fatigue and frustration)
Shorter time for each participant
(less fatigue and frustration)
 
Individual difference can be isolatedImpact of individuals difference 
Easier to detect difference between
conditions
Harder to detect difference between
conditions
 
Requires smaller sample sizeRequire larger sample size 
Counterbalance/randomize the order of
presenting conditions
Randomized assignment to conditions or matched groups 
   







Counterbalancing

All possible permutations
– 3 conditions => 3P3 = 6 permutations
     – (1,2,3), (1,3,2), (2,1,3), (2,3,1), (3,1,2), (3,2,1)

– 4 conditions => 4P4 = 24 permutations
        – (1,2,3,4), (1,2,4,3), (1,3,2,4), (1,3,4,2), …


Number of participants must be multiple of number of permutations

Balanced Latin Square

Latin Square
  – Each item occurs once in each row and column


Balanced Latin Square
  – Each item both precedes and follows each   other item an equal number of times

《拉丁方实验设计》


    原文作者:魔术师发牌问题
    原文地址: https://blog.csdn.net/moonlightpeng/article/details/80388440
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