摘要
目的:探讨前后测量设计资料中伴随的个体自然生长现象.方法:以肥胖儿童的减肥试验为例,假设有两组儿童,一组为处理组,该组儿童为肥胖儿童组接受减肥药物控制体质量;另一组为对照组,该组儿童为标准体质量儿童组,分别在8岁和10岁时测量儿童的体质量,假设两组儿童在试验前后体质量的均值分别为Y1(t1)=31.0,Y0(t1)=23.0,Y1(t2)=36.0,Y0(t2)=28.0,在处理组缺失干预时Y1(t2)=41.0.结果:用简单得分法估计处理效应,α=36.0-31.0-(28.0-23.0)=0(kg),说明两组儿童试验后的体质量无差异,处理效应不存在,但是真实的处理效应为Y1(t2)-Y1(t2)=36.0-41.0=-5.0(kg),说明处理效应是存在的,即施加干预前后儿童的体质量有差别.结论:总结了前后测量设计资料个体生长趋势的4种情况,提示我们在分析前后测量设计资料时个体自然生长问题不容忽视.
AIM: To study the individual change over time in pretest-posttest design, METHODS: Using the banting of obese children as an example, there were 2 groups : one is the treatment group with the obese children receiving drug to control weight, the other is the control group with the children of standard weight. At the age of 8 and 10, the weight was measured. The hypothesized mean of each group children weight was Y^-1 ( t1 ) = 31. 0, Y^-0(t1) =23.0, Y^-1(t2) =36.0, Y^-0(t2) =28.0. In the absence of treatment, the hypothesized mean Y^-1· (t2 ) was 41. 0. RESULTS: Using simple gain scores to estimate the treatment effect, α = 36.0 - 31.0 - (28.0 - 23.0) = 0 ( kg), this indicated that after experiment the 2 groups were not different in children weight, and the treatment effect didn't exist. But the true treatment effect was Y^-1 ( t2 ) - Y^-1· ( t2 ) = 36.0 - 41.0 = - 5.0 (kg), which showed that the treatment effect existed and the children weight was different after treatment. CONCLUSION: The 4 kinds of individual changing trends in pretest-pesttest design show the problem of the individual change can't be ignored when we analyze the data of pretest-posttest design.
出处
《第四军医大学学报》
北大核心
2006年第9期841-843,共3页
Journal of the Fourth Military Medical University
关键词
前后测量
个体生长
儿童
肥胖
pretest-posttest design
individual change