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Question 695
Statistics → Epidemiology
Classification
Question
SSBAQuestion Header
Percentile
Question Stem
A newborn's birth weight lies at the 10th percentile for its reference population. Which interpretation is correct?
Options
A
10% of observations lie above this value
B
10% of observations lie below this value
C
90% of observations lie below this value
D
The value is 10% below the mean
E
The value is one standard deviation below the mean
Explanation
A percentile is the value below which a specified percentage of observations falls. Therefore, a measurement at the 10th percentile has 10% of observations below it and 90% above it. A percentile does not describe a percentage difference from the mean or a fixed number of standard deviations from the mean.
Option Validity
A) 90%, not 10%, lie above the 10th percentile.
C) 90% lie above, rather than below, this value.
D) percentiles describe position within a distribution, not percentage deviation from the mean.
E) a percentile does not specify a fixed standard-deviation distance from the mean.
Further Reading
Review the definition and interpretation of percentiles in epidemiological data.