Sunday, March 22, 2015

Statistics 101 - Sample and Sampling Distribution

  • Point Estimation
    • We can't get population parameter directly (mean of income of your country) so that need to take samples to estimate it (inference)
    • Sample never perfect




  • Sampling and Sampling Distribution
    • Take many random samples from unknown population
    • The mean of the sampling distribution (based on taken sample means) is equal to the mean of population 
    • (랜던 샘플을 많이 가져와서 그 분포의 mean을 보면 실제 population의 mean과 같다)




  • Standard deviation of sample mean
    • Note standard deviation becomes smaller when sample size(n) increases
    • Same sample size has the same standard error of the mean
  • Standard Error
    • another name for the standard deviation. It is just the standard deviation of the sampling distribution



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