{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

321_09_slides2

# 321_09_slides2 - Week 1 Review Econ 321 Introduction to...

This preview shows pages 1–9. Sign up to view the full content.

Week 1 Review Econ 321 Introduction to Econometrics Econ 321-Stéphanie Lluis 1

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Main Steps in Statistical Analysis Population and Samples Describing data (summary statistics) Inference (CLT) Estimation Hypothesis Testing Econ 321-Stéphanie Lluis 2
Populations and Samples What is a population? What type of population would you be concerned with in your life? Population parameter What is a sample? Why use a sample rather than populations? Sample statistic to represent the best information about the unknown parameter Econ 321-Stéphanie Lluis 3

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Example for the use of Samples We are interested in a training program which is supposed to improve productivity. It would be very expensive to implement throughout a firm, particularly if it doesn’t work. Instead, we set up an experiment in which we try the program on a sample of employees at a single location (a pilot program) Econ 321-Stéphanie Lluis 4
Example for the use of Samples We experiment with a pilot program and find that productivity rose by 2% Our problem in using the pilot (sample): if we replicate the pilot throughout the firm is it reasonable to believe that we will get a 2% boost in productivity? could this just be the result of getting a “good” sample (those who happened to respond favorably to the program)? Our core problem in using samples is distinguishing between systematic effects of programs and chance outcomes Econ 321-Stéphanie Lluis 5

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Sampling Variability Samples are affected by randomness Samples are not an exact reproduction of the population 2 samples drawn from a population are unlikely to be identical The sample mean is likely to be different from (but close to) the population mean Econ 321-Stéphanie Lluis 6
Sampling Problems Survey Finds Most Women Unhappy in their Choice of Husbands A popular women’s magazine, in a survey of its subscribers, found that over 90% of them are unhappy in their choice of whom they married. Copies of the survey were mailed to the magazine 100,000’s subscribers. Surveys were returned by 5000 readers. question asked: “If you had to do it again, would you marry the same man?” Conclusion from the news article: Finding Mister right is much harder than anyone realized. Econ 321-Stéphanie Lluis 7

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Random Sample Y: family income for a population with parameter θ (population mean) unknown We use a random sample Assume it is collected for a sample of 100 families (unbiased sampling process) Y 1, Y 2 , Y n We use a sample statistic as an estimator of the population parameter Example of sample statistic?
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}