Fördelningssnedvridningar

Fördelningssnedvridningar, often translated as distribution skew or simply skewness, is a statistical term that describes the asymmetry of a probability distribution. A distribution can be skewed to the right (positively skewed) or to the left (negatively skewed). In a perfectly symmetrical distribution, the mean, median, and mode are all equal. However, when a distribution is skewed, these measures of central tendency will differ.

In a positively skewed distribution, the tail on the right side is longer or fatter than the left side. This means that there are a few unusually high values that pull the mean to the right of the median and mode. For example, income distributions are often positively skewed, with most people earning a moderate income, but a few individuals earning very high incomes.

Conversely, a negatively skewed distribution has a longer or fatter tail on the left side. In this case, there are a few unusually low values that pull the mean to the left of the median and mode. An example might be the distribution of test scores where most students perform well, but a few students score very low.

Skewness is an important characteristic to consider when analyzing data, as it can significantly impact the interpretation of statistical measures and the choice of appropriate analytical methods. Measures of skewness, such as the third standardized moment, are used to quantify the degree of asymmetry.