**Statistics part1 , Statistics part2 **

**Outlier:** An outlier is a very extreme value in data that differs significantly from other observations. and lies outside the overall distribution.

The reasons for existence of a outlier in a data is either measurement or variability.

**what is the problem with outlier ? **

As we know that outlier are extreme values in data that means it can impact **mean**, **standard deviation **and this will lead us to wrong analysis of data.

**How to recognize an outlier in data ? **

As we know that IQR has lower limit Q1 and upper limit 3*Q3 that means between 25% to 75% , we can easily avoid extreme values in data in IQR.

z-score = data values (observation) - mean of data / standard deviation.