Follow up of quality of public oriented health information on the world wide web: systematic re›evaluation

website’s contents and they were converted into three accuracy levels. In level I, more than two thirds of guideline statements were covered (28/121 (24%) web› sites); in level II, one third to two thirds of guideline statements were covered (43 (35%) websites); in level III, less than one third of guideline statements were covered (50 (41%) websites). We examined the relation between features of web› site credibility and level of accuracy of contents by cross tabulation and assessed the strength of association with Kendall’s rank correlation, which adjusts for tied ranks in the data. The value of the co› efficient (tau b) ranges from - 1 to 1. Interpretation is subjective, but values near zero may be taken to indicate no correlation whereas values near 1 indicate a strong correlation. As shown in the table, websites with description of credibility features tended to have higher levels of accuracy of contents, but this relation› ship was not strong.