Consequences
Both types of errors are problems for individuals, corporations, and data analysis. A false positive (with null hypothesis of health) in medicine causes unnecessary worry or treatment, while a false negative gives the patient the dangerous illusion of good health and the patient might not get an available treatment. A false positive in manufacturing quality control (with a null hypothesis of a product being well made) discards a product that is actually well made, while a false negative stamps a broken product as operational. A false positive (with null hypothesis of no effect) in scientific research suggest an effect that is not actually there, while a false negative fails to detect an effect that is there.
Based on the real-life consequences of an error, one type may be more serious than the other. For example, NASA engineers would prefer to waste some money and throw out an electronic circuit that is really fine (null hypothesis H0: not broken; reality: not broken; action: thrown out; error: type I, false positive) than to use one on a spacecraft that is actually broken and throw out less (null hypothesis H0: not broken; reality: broken; action: use it; error: type II, false negative). In that situation a type I error uses more money but increase mission safety, but a type II error would risk the entire mission whilst saving some money.
On the other hand, criminal courts set a high bar for proof and procedure and sometimes acquit someone who is guilty (null hypothesis: innocent; reality: guilty; test find: not guilty; action: acquit; error: type II, false negative) rather than convict someone who is innocent (null hypothesis: innocent; reality: not guilty; test find: guilty; action: convict; error: type I, false positive). In totalitarian states, the opposite may occur, with the preference to jail someone innocent, rather than allow an actual dissident to roam free. Each system makes its own choice regarding where to draw the line.
Minimizing errors of decision is not a simple issue; for any given sample size the effort to reduce one type of error generally results in increasing the other type of error. The only way to minimize both types of error, without just improving the test, is to increase the sample size, and this may not be feasible.
Read more about this topic: Type I And Type II Errors
Famous quotes containing the word consequences:
“Cultivate the habit of thinking ahead, and of anticipating the necessary and immediate consequences of all your actions.... Likewise in your pleasures, ask yourself what such and such an amusement leads to, as it is essential to have an objective in everything you do. Any pastime that contributes nothing to bodily strength or to mental alertness is a totally ridiculous, not to say, idiotic, pleasure.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)
“The middle years are ones in which children increasingly face conflicts on their own,... One of the truths to be faced by parents during this period is that they cannot do the work of living and relating for their children. They can be sounding boards and they can probe with the children the consequences of alternative actions.”
—Dorothy H. Cohen (20th century)
“War is thus divine in itself, since it is a law of the world. War is divine through its consequences of a supernatural nature which are as much general as particular.... War is divine in the mysterious glory that surrounds it and in the no less inexplicable attraction that draws us to it.... War is divine by the manner in which it breaks out.”
—Joseph De Maistre (1753–1821)