{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

010+Correlation

# If we have a large sample n 30 the 1 condence interval

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: freedom df = n − 2. If H0 is not rejected we may conclude (only in the normal case) that random variables X and Y are independent with the probability P = 1 − α. Condence interval for a correlation coecient. Assume that X and Y are normally distributed. If we have a large sample (n ≥ 30) the (1 − α)% condence interval for a correlation coecient is 1 − ρ2 ˆ ρ ± zα/2 √ ˆ n 5 A. Zhensykbaev Correlation i.e. 1 − ρ2 ˆ 1 − ρ2 ˆ ρ − zα/2 √ , ρ + zα/2 √ ˆ ˆ . n n We want to estimate ρ to within a given boundary for sampling error SE. How much will be the sample size n to accomplish this? (zα/2 (1 − ρ2 ))2 ˆ n= . (SE )2 Example 1. Consider the monthly sales revenue as a function of the monthly advertising expenditure. We base on the following table and test the hypothesis: sales revenue and advertising expenditure are independent (use α = 0.02). Advertising Sales Month expenditure Revenue xi (\$100) yi (\$1000) 1 1 1 2 2 1 3 3 2 4 4 2 5 5 4 Total xi = 15 yi = 10...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online