Aartman I H A, van Loveren C
Sociale Tandheelkunde en Voorlichtingskunde, Academisch Centrum Tandheelkunde Amsterdam.
Ned Tijdschr Tandheelkd. 2007 Apr;114(4):161-5.
In the process of evidence-based dentistry the value of each article located by means of a search action has to be determined. This is done based on the research design used. The internal validity of these designs indicates the degree to which alternative explanations might be responsible for the found results. On the basis of internal validity, research designs can be placed on the so-called ladder of 'evidence'. Clinical experimental studies (randomised controlled trials, cross-over design and split-mouth design), studies in which the researcher introduces changes or intervenes and keeps the other factors constant, have the highest level of internal validity. Observational studies (cohort study, case-control study, cross-sectional study, patient series and case study), in which groups are described and compared in their natural habit, can introduce bias, leading to a lower level of evidence. In order to assess the value of research, it is necessary to have some understanding of what these research designs are concerned with.
在循证牙科的过程中，必须确定通过搜索行动找到的每篇文章的价值。这是根据所使用的研究设计来完成的。这些设计的内部效度表明了其他解释可能对所发现结果负责的程度。基于内部效度，研究设计可以被置于所谓的“证据阶梯”上。临床实验研究（随机对照试验、交叉设计和分口设计），即研究者引入变化或进行干预并使其他因素保持不变的研究，具有最高水平的内部效度。观察性研究（队列研究、病例对照研究、横断面研究、患者系列研究和病例研究），即在自然状态下对群体进行描述和比较的研究，可能会引入偏差，导致证据水平较低。为了评估研究的价值，有必要对这些研究设计所涉及的内容有所了解。
