Basics of Probability and Statistics Week 1 Challenge

*N is a greater value than N-1.

*When divided N-1 a smaller number we will get a larger number for variance. This number near to the possible variance value for the population.

*It is always good to have a large variance for the population. This helps in further analysising data with out any bias

2. Difference between stratified and clustered sampling

Stratified sampling:

* This is a sampling method where population are divided into homogenous segment and then the sample is randomly taken from the segment.

* Randomly selected individuals are taken from all the strata.

* Imposed by researchers. This type sampling increases precision and representation.

Clustered sampling:

* This is a sampling method where the entire cluster us selected randomly. Clusters are naturally occuring group.

* All the individuals are taken from randomly selected cluster.

* Naturally occuring groups. To reduce cost and effeciency.

3.How many different samples can be created out of population of size n?

Npn = N!/(N-n)!

n = sample size

4.What is the probability of drawing 2 jacks from a pack of card?

No of cards in a deck = 52

No of jack in a deck = 4

Probalility of drawing 2 jacks from a pack of card = 1/26.

5.What is the probability that both the numbers on dice are same while rolling 2 dice?

Probability of getting 2 same number = 1/6.

6.Why standard deviation when variance can measure the dispersion in data?

Variance calulated will produce a value with unit of measurement is not similar to data. Standard deviation calculated after squaring the variance will produce unit of measurement as the data.