This study examined the question, “To what degree do two experienced chiropractors agree, as to level of subluxation, using Gonstead line-marking methods?” X-rays were submitted to two examiners who were asked to analyze films according to the Gonstead line-marking system. Degree of agreement regarding subluxations detected was compared with respect to level and direction. The direction of subluxation was considered. Cohen’s Kapa statistic was utilized to evaluate results of inter- and intra-examiner agreement. Statistical interpretation is similar to correlation coefficient (i.e., the highest level of agreement would be 1.0; the lowest level would be 0). Cohen’s has suggested terms which provide both qualitative and quantitative evaluations (i.e., the term “poor” is applied to the lowest possible level of agreement: “almost perfect” describes the highest level). The highest level of inter-examiner agreement attained in this study was “fair” and occurred at two levels. “Slight” agreement was attained at four additional levels. Intra-examiner agreement of Judge #1 was “Fair” at all levels. Intra-examiner agreement of Judge #1 was “Moderate” at four levels and “Fair” at two levels. Therefore, slight-to-fair inter-examiner agreement was observed in this study. Intra-examiner reliability revealed a fair-to-moderate level of agreement. These findings suggest that reliance upon Gonstead line-marking for detection of subluxation results in imprecise and inconsistent conclusions.
A. Plaugher G. Letter to the editor. Re: Gonstead Technique. Chiropractic 1991; 7:62.