Null hypothesis odds ratio

For each analyte concentration, assume that the null hypothesis is true. If the odds against the observed signal to noise ratio are equal to or greater than 19 to 1 reject the assumption otherwise accept it. 

This also means that the y test for binary outcomes from Section 10.5.2 can be considered a test of the null hypothesis that the population odds ratio = 1. Values of the odds ratio appropriately < 1 or appropriately > 1 are suggestive of an association between the group and the outcome. 

In this instance, independence means that the probability of the response is no more or less likely for one group versus the other. In his original paper, Fisher stated the null hypothesis slightly differently (although equivalent mathematically). The null hypothesis, after Fisher, can be stated in this form The population odds ratio of response to nonresponse for one group versus the other is equal to one. 

---