Basics of Probability and Statistics Week 1 Challenge
- The value of variance calculated from sample data is higher than the value that could have been found out by using population data. The logic of doing that is to compensate our lack of information about the population data.Population variance refers to the value of variance that is calculated from population data, and sample variance is the variance calculated from sample data. Due to this value of denominator in the formula for variance in case of sample data is ‘n-1’, and it is ‘n’ for population data. As a result both variance and standard deviation derived from sample data are more than those found out from population data.
- stratified sampling: In this type of sampling total number of population are divided in to a group and choose sample randomly in every group.clustered sampling: in this type of sampling total number of population are divided in to multiple clusters and some of the cluster selected randomly.
- There are 2^n-1 number of samplings can be created out of the population size n.
- total number of cards =52,number of jack in a deck of card=4, The probablity of choosen first card in a deck of card=4/52,the probablity of choosen second card in a deck of card =3/51, The probablity of choosen two jack in a deck of card =4/52*3/51 and the result =0.0045.
- the total number of samples rolling a dice 2 times =36, the chances of getting same numbers =6, The proablity of getting both number dice =6/36 and the answer is 1/6.
- variance can measure the despersion in data with squared value to convert it into mean value standards deviation is required. in other word the out come units are squared in variance and to balancing the units standard deviation is required.