This article may be expanded with text translated from the corresponding article in Tamil. (August 2020) Click [show] for important translation instructions.
View a machine-translated version of the Tamil article.
Machine translation like DeepL or Google Translate is a useful starting point for translations, but translators must revise errors as necessary and confirm that the translation is accurate, rather than simply copy-pasting machine-translated text into the English Wikipedia.
Do not translate text that appears unreliable or low-quality. If possible, verify the text with references provided in the foreign-language article.
You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation. A model attribution edit summary is Content in this edit is translated from the existing Tamil Wikipedia article at [[:ta:சதவீத முனைப்புள்ளி]]; see its history for attribution.
You should also add the template ((Translated|ta|சதவீத முனைப்புள்ளி)) to the talk page.
For more guidance, see Wikipedia:Translation.

A **percentage point** or **percent point** is the unit for the arithmetic difference of two percentages. For example, moving up from 40 percent to 44 percent is an increase of 4 percentage points, but a 10-percent increase in the quantity being measured.^{[1]} In literature, the unit is usually either written out,^{[2]} or abbreviated as *pp* or *p.p.* to avoid ambiguity. After the first occurrence, some writers abbreviate by using just "point" or "points".

Consider the following hypothetical example: In 1980, 50 percent of the population smoked, and in 1990 only 40 percent of the population smoked. One can thus say that from 1980 to 1990, the prevalence of smoking decreased by 10 *percentage points* (or by 10 percent of the population) or by *20 percent* when talking about smokers only - percentages indicate proportionate part of a total.

Percentage-point differences are one way to express a risk or probability. Consider a drug that cures a given disease in 70 percent of all cases, while without the drug, the disease heals spontaneously in only 50 percent of cases. The drug reduces absolute risk by 20 percentage points. Alternatives may be more meaningful to consumers of statistics, such as the reciprocal, also known as the number needed to treat (NNT). In this case, the reciprocal transform of the percentage-point difference would be 1/(20pp) = 1/0.20 = 5. Thus if 5 patients are treated with the drug, one could expect to heal one more case of the disease than would have occurred in the absence of the drug.

For measurements involving percentages as a unit, such as, growth, yield, or ejection fraction, statistical deviations and related descriptive statistics, including the standard deviation and root-mean-square error, the result should be expressed in units of percentage points instead of percentage.^{[citation needed]} Mistakenly using percentage as the unit for the standard deviation is confusing, since percentage is also used as a unit for the relative standard deviation, i.e. standard deviation divided by average value (coefficient of variation).

- Percentage (%) 1 part in 100
- Per mille (‰) 1 part in 1,000
- Basis point (bp) difference of 1 part in 10,000
- Permyriad (‱) 1 part in 10,000
- Per cent mille (pcm) 1 part in 100,000
- Baker percentage