Stolwijk A M, Straatman H, Zielhuis G A
Department of Epidemiology, University of Nijmegen, The Netherlands.
J Epidemiol Community Health. 1999 Apr;53(4):235-8. doi: 10.1136/jech.53.4.235.
A statistical test that allows for adjustment of confounding can be helpful for the study of seasonal patterns. The aim of this article is to supply a detailed description of such a method. An example of its application is given.
A statistical test is presented that retains the information on the connection of time periods by describing the seasonal pattern as one sine and one cosine function. Such functions can be included into a regression model. The resulting form of the seasonal pattern follows a cosine function with variable amplitude and shift.
The test is shown to be applicable to test for seasonality. Not only one cosine function per time period, but also a mixture of cosine functions can be used to describe the seasonal pattern. Adjustment for confounding effects is possible.
This method for studying seasonal patterns can be applied easily in a regression model. Adjusted prevalences and odds ratios can be calculated.
一种能够对混杂因素进行调整的统计检验方法,有助于对季节性模式的研究。本文旨在详细描述这样一种方法,并给出其应用实例。
提出一种统计检验方法,该方法通过将季节性模式描述为一个正弦函数和一个余弦函数来保留时间段之间联系的信息。这些函数可以纳入回归模型。由此得到的季节性模式形式遵循一个具有可变振幅和偏移的余弦函数。
该检验方法被证明适用于季节性检验。不仅每个时间段可以使用一个余弦函数,还可以使用余弦函数的混合来描述季节性模式。可以对混杂效应进行调整。
这种研究季节性模式的方法可以很容易地应用于回归模型中。可以计算调整后的患病率和比值比。