## 字幕表 動画を再生する

• The most commonly used tool to measure asymmetry is skewness.

• This is the formula to calculate it.

• Almost always, you will use software that performs the calculation for you, so in this

• lesson, we will not get into the computation, but rather the meaning of skewness.

• So, skewness indicates whether the observations in a data set are concentrated on one side.

• Skewness can be confusing at the beginning, so an example is in place.

• Remember frequency distribution tables from previous lectures?

• Here we have three data sets and their respective frequency distributions.

• We have also calculated the means, medians and modes.

• The first data set has a mean of 2.79 and a median of 2, hence the mean is bigger than

• the median.

• We say that this is a positive or right skew.

• From the graph, you can clearly see that the data points are concentrated on the left side.

• Note that the direction of the skew is counterintuitive.

• It does not depend on which side the line is leaning to, but rather to which side its

• tail is leaning to.

• So, right skewness means that the outliers are to the right.

• It is interesting to see the measures of central tendency incorporated in the graph.

• When we have right skewness, the mean is bigger than the median, and the mode is the value

• with the highest visual representation.

• In the second graph, we have plotted a data set that has an equal mean, median and mode.

• The frequency of occurrence is completely symmetrical and we call this a zero or no

• skew.

• Most often, you will hear people say that the distribution is symmetrical.

• For the third data set, we have a mean of 4.9, a median of 5 and a mode of 6.

• As the mean is lower than the median, we say that there is a negative or left skew.

• Once again, the highest point is defined by the mode.

• Why is it called a left skew, again?

• That’s right, because the outliers are to the left.

• Alright.

• So, why is skewness important?

• Skewness tells us a lot about where the data is situated.

• As we mentioned in our previous lesson, the mean, median and mode should be used together

• to get a good understanding of the dataset.

• Measures of asymmetry like skewness are the link between central tendency measures and

• probability theory, which ultimately allows us to get a more complete understanding of

• the data we are working with.

The most commonly used tool to measure asymmetry is skewness.

ワンタップで英和辞典検索 単語をクリックすると、意味が表示されます

# 歪度 (Skewness)

• 7 1
林宜悉 に公開 2021 年 01 月 14 日