kvartilösa

Kvartilösa is a term used in some Swedish-language statistical discussions to describe data sets or distributions for which quartiles are not well-defined or are difficult to interpret. It is not part of formal statistical nomenclature, but it is used to highlight situations in which reporting Q1 (the 25th percentile) and Q3 (the 75th percentile) is unreliable or ambiguous.

The concept arises in several common situations. One is data that have substantial censoring or truncation, where a large portion of observations share the same value or fall outside the measurable range. Another is data sets with many tied values, where different quartile calculation rules or interpolation methods yield different results. A third is very small sample sizes, where the quartile estimates can vary widely depending on the chosen method for handling ties or for interpolation. In all these cases, quartile-based summaries may be misleading as a descriptor of central tendency or spread.

Practical implications are that analysts may supplement or replace quartiles with alternative summaries. Reporting the median along with a range or confidence interval, using robust quantile estimation methods, or explicitly stating the method used to derive quartiles can improve interpretability. In some instances, it is preferable to present percentiles at fixed confirmations or to focus on other measures such as the interquartile range if it remains meaningful.

See also: quartile, percentile, median, interquartile range, data censoring.