lect29 - Correlation coefficient is dimensionless, ranges...

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UCF Physics: AST 5765/4762: (Advanced) Astronomical Data Analysis Fall 2009 Lecture Notes: 29. Cross Correlation 1 Check In: 10:30 — 10:35, 5 min Questions? 2 Cross Correlation: 10:35 – 11:20, 45 min Use cross-correlation to find shift: C ( s ) = i -∞ f ( x + s ) g ( x ) dx (1) Evaluate for reasonable range of shifts, max is best alignment For spectrum shifts (e.g., Doppler), x = λ and s = Δ λ Discrete math, must generally: Generally, want to use f - ¯ f and g - ¯ g Generally need to pad data (see demo) Note: This is different from the correlation coefficient!
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Unformatted text preview: Correlation coefficient is dimensionless, ranges [-1,1] ( x, y ) = N i =1 ( x- x )( y- y ) N x y (2) It tests for trends (correlation) in sets of (x,y) datapoints Cross correlation measures shifts between two datasets in the same independent variable Assess the UNNORMALIZED correlation to do this Demo: 19crosscor , start with Correlation_examples.png 3 Q&A: 11:20 11:45, 25 min 1...
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This note was uploaded on 11/09/2009 for the course AST 4762 taught by Professor Harrington during the Fall '09 term at University of Central Florida.

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