what percentile would say is abnormal?
ChatGPT said:
In statistics, the term "abnormal" often corresponds to values that fall in the extreme tails of a distribution. Typically, these extremes are defined using percentiles. Here's how percentiles can relate to what is considered "abnormal":
- Below the 5th percentile: Values below the 5th percentile are considered unusually low. This means only 5% of the population or data falls below this point.
- Above the 95th percentile: Values above the 95th percentile are considered unusually high. This means only 5% of the population or data exceeds this point.
So, in many cases, values
below the 5th percentile or above the 95th percentile are often considered "abnormal." This corresponds to the outer 10% of a distribution, with the middle 90% generally considered "normal."
In more extreme cases, some contexts may define "abnormal" as being below the 2.5th percentile or above the 97.5th percentile, representing the outer 5% of a distribution (2.5% on each tail).
You said:
would the 15 percentile be considered abnormal?
ChatGPT said:
The 15th percentile is not typically considered "abnormal" in most contexts. While it does indicate a value that is lower than 85% of the population or dataset, it is still within a range that many would consider "low" rather than "abnormal."
Here’s a breakdown:
- Normal Range: Often considered between the 5th and 95th percentiles.
- Low/High but not Abnormal: Percentiles between 5th-15th or 85th-95th. These may be flagged as "low" or "high" but are generally not outside the bounds of normal variation.
- Abnormal Range: Typically below the 5th percentile or above the 95th percentile.
So, while the 15th percentile might be lower than average, it usually doesn't qualify as "abnormal." It suggests a value that is on the lower side of the normal distribution.