tag:blogger.com,1999:blog-192445222306631874.post8722985674485581974..comments2022-03-30T02:22:30.689-07:00Comments on Xenia Schmalz's blog: P-values 101: An attempt at an intuitive but mathematically correct explanationXenia Schmalzhttp://www.blogger.com/profile/02238923475669435076noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-192445222306631874.post-62692033606705257162019-02-19T17:54:42.474-08:002019-02-19T17:54:42.474-08:00Not all agree. https://errorstatistics.com/2017/04...Not all agree. https://errorstatistics.com/2017/04/15/if-youre-seeing-limb-sawing-in-p-value-logic-youre-sawing-off-the-limbs-of-reductio-arguments/Anonymoushttps://www.blogger.com/profile/13594876772432068373noreply@blogger.comtag:blogger.com,1999:blog-192445222306631874.post-17915746795355978382019-02-19T04:41:04.766-08:002019-02-19T04:41:04.766-08:00The use of p-values is predicated on what might be...The use of p-values is predicated on what might be called the *probabilistic modus tollens*. <br /><br />If a variable has no effect (A), then the groups will *probably* not differ substantially (B)<br /><br />The groups differ substantially (~B)<br /><br />Therefore the variable in question *probably* has an effect (~A). <br /><br />Don't recognize that from your logic class? Because it ain't logic. In any event, one can accept the probabilistic modus tollens but then a curious thing happens: if you ask "how probable is it that the null is false? the answer can only be, "I don't know." That is because *if* the null *is* false, the p-value becomes quantitatively meaningless!Glenhttps://www.blogger.com/profile/01005467685190887023noreply@blogger.comtag:blogger.com,1999:blog-192445222306631874.post-52948212428161705122019-02-18T19:26:21.052-08:002019-02-18T19:26:21.052-08:00Some people get antsy when p-values are called con...Some people get antsy when p-values are called conditional probabilities (https://statmodeling.stat.columbia.edu/2013/03/12/misunderstanding-the-p-value/#comment-143508). Personally I'm a Bayesian so (like Gelman in the linked thread) I've got no problem with it. But at least some frequentists, be they practicing statisticians like Larry Wasserman or philosophers of science and statistics like Deborah Mayo, would tell you that calling a p-value a conditional probability is wrong.Anonymoushttps://www.blogger.com/profile/13594876772432068373noreply@blogger.comtag:blogger.com,1999:blog-192445222306631874.post-85445889914516517312019-02-13T08:59:07.774-08:002019-02-13T08:59:07.774-08:00Great summary, not just of what p-values are but o...Great summary, not just of what p-values are but of many other useful concepts (that have to do with the replication crisis) as well. Thanks very much.Gordon Ingramhttps://www.blogger.com/profile/06466059168771018808noreply@blogger.com