This level of risk is called the significance. The process of data dredging involves testing multiple hypotheses using a single data set by exhaustively searching-perhaps for combinations of variables that might show a correlation, and perhaps for groups of cases or observations that show differences in their mean or in their breakdown by some other variable.Ĭonventional tests of statistical significance are based on the probability that a particular result would arise if chance alone were at work, and necessarily accept some risk of mistaken conclusions of a certain type (mistaken rejections of the null hypothesis). This is done by performing many statistical tests on the data and only reporting those that come back with significant results. If the crane is mounted on a barge, the entire vessel is referred to as a dredger.Misuse of data analysis A humorous example of a result produced by data dredging, showing a coincidental correlation between the number of letters in Scripps National Spelling Bee's winning word and the number of people in the United States killed by venomous spiders.ĭata dredging (also known as data snooping or p-hacking) is the misuse of data analysis to find patterns in data that can be presented as statistically significant, thus dramatically increasing and understating the risk of false positives. The crane could be located on the bank, or perhaps mounted on a barge. Developing this idea further, a motorized crane equipped with a drag bucket or clamshell that is used to scoop material from the bottom of a body of water is also a dredger. For example, a scoop attached to the end of a rope or pole by which a man can draw sediments up from the bottom of a pond is a dredger. A dredger is any device, machine, or vessel that is used to excavate and remove material from the bottom of a body of water. Dredging is also used as a technique for fishing for certain species of edible clams and crabs, see fishing dredge.

It is also used as a way to replenish sand on some public beaches, where sand has been lost because of coastal erosion.

This technique is often used to keep waterways navigable. Dredging Dredging is an excavation activity or operation usually carried out at least partly underwater, in shallow seas or fresh water areas with the purpose of gathering up bottom sediments and disposing of them at a different location.

Dredge synonym