𝔖 Bobbio Scriptorium
✦   LIBER   ✦

S34.3: Inference from empty contingency tables

✍ Scribed by Gerd Rippin; Marcus Kutschmann


Publisher
John Wiley and Sons
Year
2004
Tongue
English
Weight
72 KB
Volume
46
Category
Article
ISSN
0323-3847

No coin nor oath required. For personal study only.

✦ Synopsis


If only the marginal counts of a contingency table are known, inference regarding a statistic e.g. like the log odds ratio is still possible. In the following a 2*2 contingency table and the log odds ratio as the interesting statistic are assumed, although the methodology is more general. Given the marginal counts all possible contingency tables are determined, such that for every possible table the estimated log odds ratio can be calculated. All resulting estimates per contingency table can be averaged in a first step e.g. by using the hypergeometric weighting under H0, such that a first overall estimate of the log odds ratio together with its standard error are available. This estimate is used for assigning new weights to the estimates per contingency table corresponding to the normal density of the overall estimated log odds ratio. After these initial steps a MCMC method is applied, by drawing in a first step from the distinct distributions of the log odds ratios of the contingency tables. The averaging takes place corresponding to the weights of the last step, such that a new overall estimate is calculated. Then, secondly, also the new weights are calculated by the density of the normal distribution corresponding to the new overall estimate as described before. The results from the procedure are consistent with common sense. If e.g. an exposition is very common but the disease is very rare, it is unlikely that the exposition is a strong risk factor for the disease. The disadvantage of the method is its potential misuse as all one has to obtain are percentages of two variables and a claim of an association can be made without even bothering having sampled data. Thus, ambiguity and multiple testing become significant issues. If there is no way to sample the corresponding variables, the described MCMC approach may be sensible to apply, but if there is a way, it cannot replace at all the sound scientific work of sampling data and to conduct well-designed studies.


πŸ“œ SIMILAR VOLUMES


On analytical methods and inferences for
✍ Richard M. Engeman; George D. Swanson πŸ“‚ Article πŸ“… 1991 πŸ› Elsevier Science 🌐 English βš– 283 KB

Analysis of 2 x 2 contingency tables is not as trivial as it appears. The choice of the statistical test can affect the inferences resulting from data analysis, especially at small sample sizes. Canned statistical programs do not necessarily lead to an appropriate test. These points are demonstrated