## Howard-Wolowitz one year ago Mean and Standard deviation question!

1. hartnn

you know the formulas, right?

2. Howard-Wolowitz

No not for this

3. Howard-Wolowitz

um what is the formula called?

4. hartnn

mean is just the average, sum all the values and divide by the number of values. first find mean, you'll need it for std deviation

5. hartnn

std deviation is the square root of variance and variance is $$\Large {Var}(X) = \frac{1}{n} \sum \limits_{i=1}^n (x_i - \mu)^2.$$

6. Howard-Wolowitz

problem, Im not sure where to put some of the values

7. hartnn

$$\Large \mu = \dfrac{1.13+1.02+1.23+1.06+1.16}{5}$$

8. Howard-Wolowitz

it is linear so 1.12u

9. hartnn

yes, thats mean now calculate variance using the formula

10. hartnn

n = 5 $$\mu$$ =1.12

11. Howard-Wolowitz

i got 1.25u

12. hartnn

$$mean = \mu = 1.12$$ $$\Large {Var}(X) = \dfrac{1}{n} \sum \limits_{i=1}^n (x_i - \mu)^2 \\ \Large = \dfrac{1}{5} [(1.13 - 1.12)^2+(1.02 - 1.12)^2 \\ \Large +(1.23 - 1.12)^2+(1.06 - 1.12)^2 +(1.16 - 1.12)^2]$$

13. hartnn

calculating that has nothing to do with statistics you can use calculator or web to do that calculation for you

14. Howard-Wolowitz

ok i got 8.43

15. hartnn
16. Howard-Wolowitz

ok this time i got 0.00685

17. hartnn

see the example here, https://www.easycalculation.com/statistics/standard-deviation.php

18. Howard-Wolowitz

Question: is standard deviation and variance considered the same thing? or do I find it now?

19. hartnn

they are conceptually different, but one formula to find variance, and square root of variance is std deviation

20. Howard-Wolowitz

Now, my last question is basically asking if mean and median are or are not conflicting between which is the central value.. right?

21. hartnn

When the values of items in the data set are not important BUT the measure which divides the distribution into two equal parts is required, Median is considered as the measure of central tendency otherwise Mean is considered