How does skew and range affect standard deviation

In summary, the effects of skewness on mean, range, and standard deviation can be clearly seen in the accompanying graphic. A higher skewness parameter results in a narrower spread of data, leading to a smaller range and standard deviation. This is demonstrated by the differences in lengths of the arrows in the graphic. Additionally, understanding how mean, range, and standard deviation are calculated can provide a conceptual and mathematical explanation for these differences. However, it is important to note that the visual demonstration may be difficult to interpret without proper explanation and understanding of the concepts.
  • #1
Mr Davis 97
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Homework Statement



How does skew and range affect the standard deviation; does one affect it more than the other?

Homework Equations



None

The Attempt at a Solution



It seems as though if the range increases, the standard deviation increases because the SD is a measure of how spread apart from the mean each observation is. However, I have no idea how skew for a data set would affect the SD of that data set. Also, I am not really sure what the question is asking.
 
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  • #2
Mr Davis 97 said:

Homework Statement



How does skew and range affect the standard deviation; does one affect it more than the other?

Homework Equations



None

The Attempt at a Solution



It seems as though if the range increases, the standard deviation increases because the SD is a measure of how spread apart from the mean each observation is. However, I have no idea how skew for a data set would affect the SD of that data set. Also, I am not really sure what the question is asking.
How is skew defined in your textbook? Range, standard deviation, and mean are pretty well-known terms, but skew is not so well known.
 
  • #3
The effects of skewness on mean, range, and standard deviation are clearly demonstrated in the accompanying graphic. Additionally, if you understand how mean, range, and standard deviation are calculated, the differences in the mean, range, and standard deviation between a Normal distribution with skewness parameter 0 and a skewed Normal distribution with skewness parameter 2 should be intuitively obvious and with an appropriate amount of thought, these differences should be able to be explained conceptually and mathematically.

Note: While the two pairs of arrows were meant to demonstrate visually the phenomena discussed above, I am afraid they serve no value without some explanation. Therefore, the point of the two pairs of arrows (pun intended) is to demonstrate by the lengths of corresponding arrows that the skewed data is less dispersed in both directions than the Normal data at a randomly selected level. I suspect the vertical lines "hide" the differences in the lengths of the arrows, but if you measure them, the differences in lengths become obvious.

I will be delighted to clarify any points or answer any questions and would appreciate any comments, suggestions, or criticisms.

Jim
 

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Related to How does skew and range affect standard deviation

1. How does skewness affect standard deviation?

The measure of skewness indicates the asymmetry in a distribution. Positive skewness means that the tail of the distribution is longer on the right side, while negative skewness means that the tail is longer on the left side. This can affect the standard deviation because extreme values on one side of the distribution can pull the mean in that direction, resulting in a larger standard deviation.

2. Can a distribution with a large range have a low standard deviation?

Yes, a distribution with a large range can have a low standard deviation if the data points are close to each other and the majority of the data is clustered around the mean. However, if the data points are spread out, the standard deviation will also be large.

3. How does the range affect the standard deviation?

The range is the difference between the highest and lowest values in a dataset. A larger range indicates more variability in the data, which can result in a larger standard deviation. This is because the standard deviation is a measure of how much the data points deviate from the mean, and a larger range means there is more variation from the mean.

4. Is the standard deviation affected by outliers?

Yes, outliers can significantly affect the standard deviation. Outliers are data points that are significantly different from the rest of the data, and they can pull the mean in their direction, resulting in a larger standard deviation. Therefore, it is important to identify and handle outliers appropriately in data analysis.

5. Can the standard deviation be negative?

No, the standard deviation cannot be negative. It is a measure of dispersion, and it represents the average distance of the data points from the mean. Therefore, it is always a positive value or zero if all the data points are the same.

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