# Estimating the FUTURE!

## Main Question or Discussion Point

Suppose I have a radar gun that can measure velocity with an internal error with a mean of 3 m/s and a standard deviation of 1m/s on that error
eg velocity
10 +- 2.8
6 +- 3.1
21 +- 3.2

and so on. Now I want to make a prediction of the future when I get a new radar gun. It will have an internal error of roughly 1m/s
How then do I scale the std deviation? by a factor of three?
Thanks all!

Last edited:

Related Set Theory, Logic, Probability, Statistics News on Phys.org
A change in the mean doesn't have to change the standard deviation.
The standard deviation could still be 1m/s.

For example {3,4,5,3,4,5} and {7,8,9,7,8,9} have the same standard deviation but different means.

You really need more data to establish a future variance and standard deviation.

If you were to make an educated guess would it make sense to scale the std?
What other data would you need?

If you were to make an educated guess would it make sense to scale the std?