Which measure of central tendency is the lowest of the common measures of central tendency when the data is negatively skewed?
Mean will be the lowest number.
If data shows negatively skewed (or left skewed) distribution, it will have a long left tail, because of many less frequent small value observations, and most frequent bigger value observations. In this type of distribution, Mode takes the maximum value, followed by median and lowest value is of mean.
The reason behind it is, Mode represents a most frequent observation and is never affected by maximum and minimum values of data, Median represents a observation which cut data into two halves,depending on frequency of observation, whereas Mean is average of all observations and gets influenced largely by extreme values as well as frequencies.
Thus is case of negatively skewed distributions, mean gets pulled towards left side of the curve, under influence of small value observations, while mode gets a maximum value.
Check the following image for more understanding