Introduction to Statistical Methods and Econometrics — Economics STD 12 — Question
Tamilnadu BoardEnglish MediumSTD 12EconomicsIntroduction to Statistical Methods and Econometrics3 Marks
Question
Briefly explain the calculation of standard deviation individual series steps?
✓
Answer
Steps:
1. Find out the actual mean of given data $(\bar{X})$
2. Find out the deviation of each value from the mean $(x=X-\bar{X})$
3. Square the deviations and take the total of squared deviations $\Sigma x^2$
4. Divided the total $\Sigma x^2$ by the number of observation ( $\frac{\Sigma x^2}{n}$ )
5. The square root of $\left(\frac{\Sigma x^2}{n}\right)$ is standard deviation.
$\sigma=\sqrt{\left(\frac{\sum x^2}{n}\right)} \text { or } \sqrt{\left(\frac{\sum(x-\bar{x})^2}{n}\right)}$
$\frac{\Sigma x^2}{n}=\text { Variance }=\frac{\Sigma(x-\bar{x})^2}{n}$
When the sample size is less than 30 , variance $=\frac{\Sigma(x-\bar{x})^2}{n-1}$
When $n =$ number of observations.
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