# Statinference

## Probability

• Population quantity summarizing the randomness of a random experiment
• Inherently when we are talking about probability we are talking about population
• Data in hand is just an aid to model this probability

## Estimation

• Sample mean is itself a random variable and will have it;s own distribution, expected value
• The center of this distribution of the sample mean is same as that of observation making the sample mean an ‘unbiased’ estimator of population mean
• Expected values are properties of distribution
• Sample mean is an estimate of pipulation mean.
• Center of mass of population = population mean
• Center of mass of observations - Sample mean