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Definition of Post hoc

Babylon English

of or relating to the fallacy of arguing that because one thing happens after another the first event was a cause of the second event, being the fallacy of arguing that because one thing happens after another the first event was a cause of the second event; developed after the fact
logical fallacy that simply because one thing happens after another the first event was a cause of the second event
Post hoc Definition from Arts & Humanities Dictionaries & Glossaries
JM Latin-English Dictionary
After this
Post hoc Definition from Science & Technology Dictionaries & Glossaries
Electronic Statistics Textbook
Usually, after obtaining a statistically significant F test from the ANOVA , one wants to know which means contributed to the effect; that is, which groups are particularly different from each other. One could of course perform a series of simple t-tests to compare all possible pairs of means. However, such a procedure would capitalize on chance. The reported probability levels would actually overestimate the statistical significance of mean differences. For example, suppose you took 20 samples of 10 random numbers each, and computed 20 means. Then, take the group (sample) with the highest mean and compare it with that of the lowest mean. The t-test for independent samples will test whether or not those two means are significantly different from each other, provided that they were the only two samples taken. Post-hoc comparison techniques on the other hand, specifically take into account the fact that more than two samples were taken. They are used as either hypothesis testing or exploratory methods.
For more information, see the ANOVA chapter.
Post hoc Definition from Encyclopedia Dictionaries & Glossaries
Wikipedia English - The Free Encyclopedia
Post hoc ergo propter hoc (Latin: "after this, therefore because of this") is a logical fallacy (of the questionable cause variety) that states "Since event Y followed event X, event Y must have been caused by event X." It is often shortened to simply post hoc. It is subtly different from the fallacy cum hoc ergo propter hoc ("with this, therefore because of this"), in which two things or events occur simultaneously or the chronological ordering is insignificant or unknown. Post hoc is a particularly tempting error because temporal sequence appears to be integral to causality. The fallacy lies in coming to a conclusion based solely on the order of events, rather than taking into account other factors that might rule out the connection.

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In the design and analysis of experiments, post-hoc analysis (from Latin post hoc, "after this") consists of looking at the data—after the experiment has concluded—for patterns that were not specified a priori. It is sometimes called by critics data dredging to evoke the sense that the more one looks the more likely something will be found. More subtly, each time a pattern in the data is considered, a statistical test is effectively performed. This greatly inflates the total number of statistical tests and necessitates the use of multiple testing procedures to compensate. However, this is difficult to do precisely and in fact most results of post-hoc analyses are reported as they are with unadjusted p-values. These p-values must be interpreted in light of the fact that they are a small and selected subset of a potentially large group of p-values. Results of post-hoc analyses should be explicitly labeled as such in reports and publications to avoid misleading readers.

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Post hoc Definition from Medicine Dictionaries & Glossaries
Aids Glossary
after the fact.
Post hoc Definition from Language, Idioms & Slang Dictionaries & Glossaries
WordNet 2.0

1. the logical fallacy of believing that temporal succession implies a causal relation
(synonym) post hoc ergo propter hoc
(hypernym) logical fallacy