Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
Stat Med. 2011 Feb 28;30(5):531-40. doi: 10.1002/sim.3898. Epub 2011 Feb 2.
To develop statistical tests for comparing trend curves of study outcomes between two socio-demographic strata across consecutive time points, and compare statistical power of the proposed tests under different trend curves data, three statistical tests were proposed. For large sample size with independent normal assumption among strata and across consecutive time points, the Z and Chi-square test statistics were developed, which are functions of outcome estimates and the standard errors at each of the study time points for the two strata. For small sample size with independent normal assumption, the F-test statistic was generated, which is a function of sample size of the two strata and estimated parameters across study period. If two trend curves are approximately parallel, the power of Z-test is consistently higher than that of both Chi-square and F-test. If two trend curves cross at low interaction, the power of Z-test is higher than or equal to the power of both Chi-square and F-test; however, at high interaction, the powers of Chi-square and F-test are higher than that of Z-test. The measurement of interaction of two trend curves was defined. These tests were applied to the comparison of trend curves of vaccination coverage estimates of standard vaccine series with National Immunization Survey (NIS) 2000-2007 data.
为了开发用于比较两个社会人口阶层在连续时间点上的研究结果趋势曲线的统计检验方法，并比较不同趋势曲线数据下的拟议检验的统计功效，提出了三种统计检验方法。对于具有独立正态性假设的大样本量和跨连续时间点的情况，开发了 Z 和卡方检验统计量，它们是两个阶层在每个研究时间点的结果估计和标准误差的函数。对于具有独立正态性假设的小样本量，生成了 F 检验统计量，它是两个阶层的样本量和整个研究期间的估计参数的函数。如果两个趋势曲线大致平行，则 Z 检验的功效始终高于卡方检验和 F 检验的功效。如果两个趋势曲线在低交互处交叉，则 Z 检验的功效高于或等于卡方检验和 F 检验的功效；然而，在高交互处，卡方检验和 F 检验的功效高于 Z 检验的功效。定义了两个趋势曲线的交互度量。这些检验方法应用于比较标准疫苗系列接种覆盖率估计的趋势曲线与 2000-2007 年国家免疫调查（NIS）数据。
