Standard deviation in exponential distribution

In summary, the standard deviation has the same role for all distributions, indicating the spread covering most of the probability. However, for the normal distribution, the percentages covered are exact, while for others it gives a rough idea. For an exponential distribution, the standard deviation is equal to the mean, and the range of values within one standard deviation from the mean is 0 to 2 times the mean. This is different from the '68-95-99.7' rule of the normal distribution. The standard distributions of different probability density functions have different probabilities for X being within one standard deviation, but they still provide a good indication of how much the values of X are spread out.
  • #1
oneamp
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0
What is the significance of the standard deviation (equal to the mean) in an exponential distribution? For example, as compared to the standard deviation in the normal distribution, which conforms to the '68-95-99.7' rule?
thanks
 
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  • #2
Qualitatively the standard deviation has the same role for all distributions, indicating the spread covering most of the probability. For the normal distribution, the percentages covered are exact, while for others it gives a rough idea.
 
  • #3
Thank you. Additionally, is it true that the standard deviation for an exponential distribution is the same as the mean? Does this imply that the first standard deviation for an exponential distribution is, on either side of the mean 'u', 0 - u, and u - 2u?

Thank you again
 
  • #4
oneamp said:
Thank you. Additionally, is it true that the standard deviation for an exponential distribution is the same as the mean?
Yes.
Does this imply that the first standard deviation for an exponential distribution is, on either side of the mean 'u', 0 - u, and u - 2u?
Yes, 0<X<2u would be the range of X that represents "within one standard deviation of the mean". The probabilities are quite different from the '68-95-99.7' rule of the normal distribution. For the exponential, the probability of 0<X<2u is 1-e^-2 = 0.865, not 0.68. The probabilities of 1, 2, and 3 standard deviations from the mean are 0.865, 0.95, and 0.98, respectively.
 
  • #5
Thank you. What is the point of having 'standard distributions' with different probabilities for X contained therein? What is 'standard' about that?
 
  • #6
Although the standard distributions of different probability density functions do not give the same probabilities of X being within one standard distribution, they still have a very good use. They tell you how much you can expect, on average, the value of X to differ from its mean. So it gives the best single-number indication of how much the values of X are spread out.
 
  • #7
Thank you very much
 

FAQ: Standard deviation in exponential distribution

What is standard deviation in exponential distribution?

Standard deviation in exponential distribution is a measure of how much the values of a data set deviate from the mean in an exponential distribution. It is used to quantify the spread of the data and is calculated by taking the square root of the variance.

How is standard deviation in exponential distribution calculated?

The formula for calculating standard deviation in exponential distribution is √λ2, where λ is the rate parameter. Alternatively, it can also be calculated by taking the square root of the second moment of the distribution.

What does a high standard deviation in exponential distribution indicate?

A high standard deviation in exponential distribution indicates that the data points are spread out over a wide range of values, meaning that there is a high degree of variability in the data. This could be due to factors such as outliers or a large variance in the data set.

How does standard deviation in exponential distribution relate to the mean?

Standard deviation in exponential distribution is closely related to the mean, as it measures the average distance of the data points from the mean. A larger standard deviation indicates a greater distance from the mean, while a smaller standard deviation means the data points are closer to the mean.

What is the significance of standard deviation in exponential distribution?

Standard deviation in exponential distribution is an important statistical measure that helps to understand the variability of data. It is commonly used in hypothesis testing and confidence interval calculations, and it can also be used to compare the spread of data between different exponential distributions.

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