How does skew and range affect standard deviation

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SUMMARY

The discussion focuses on the relationship between skewness, range, and standard deviation (SD) in statistical data sets. It is established that an increase in range directly correlates with an increase in standard deviation, as SD measures the dispersion of observations from the mean. Skewness, while less commonly understood, also affects SD; a skewed distribution exhibits less dispersion compared to a normal distribution. The differences in mean, range, and standard deviation between a normal distribution and a skewed normal distribution are significant and can be analyzed both conceptually and mathematically.

PREREQUISITES
  • Understanding of standard deviation and its calculation
  • Familiarity with skewness and its definition
  • Knowledge of normal distribution characteristics
  • Ability to interpret graphical representations of data distributions
NEXT STEPS
  • Research the mathematical definitions and calculations of skewness
  • Study the properties and implications of normal distributions versus skewed distributions
  • Explore graphical methods for visualizing skewness and dispersion
  • Learn about the impact of skewness on statistical measures beyond standard deviation
USEFUL FOR

Statisticians, data analysts, students studying statistics, and anyone interested in understanding the effects of skewness and range on standard deviation.

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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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.
 
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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