# Probability and I have a question about standard deviation.

• agus
In summary, the conversation discusses the use of standard deviation in determining a suitable range for distance data and the relation between a standard deviation graph and the data. The conversation also mentions the use of Chebyshev's inequality in determining the probability that all data falls within a certain range of the mean. Excel is mentioned as a tool for plotting the standard normal distribution curve, but the speaker is unsure how to relate this graph to their data to see the deviation. They also inquire about the meaning of h, which is clarified as the number of standard deviations on either side of the mean.

#### agus

I have a question about standard deviation. If I have a hundred of distance data, how can I use standard deviation to choose a suitble range of the distance. What is the relation between standard deviation graph and my data. I can plot a graph using mean and std of the data, but do not know how to relate that graph to my data.

Thank You.

What do YOU mean by "a suitable range"? What do YOU mean by "standard deviation graph"? HOW are you drawing a "graph using mean and std of the data"? A graph of what?

Perhaps you are trying to decide what range you should use in a graph of your data- TCebyshev's inequality might apply here. The probability that all data are between the mean minus h times the standard deviation and the mean plus h times the standard deviation is 1- 1/h2.

Thank You very much HallsofIvy
I used excel to plot the standard normal distribution curve using mean and std of the data. But, I don't know how relate this graph with my data to see the deviation of the data. I want to see what is the deviation of data.Or the propability that the data are in a certain value between the mean.

Code:
The probability that all data are between the mean minus h times,1- 1/h2.

What is h?

tq

Exactly what I said it was! h is the number of standard deviations on either side of the mean you are including in your graph.