1. Soundpost Questions, re: T&M 1.Equipment acceptable?Henri 2.Dated chronologies?Malcolm 3.t value?Paul 4.Instrument chronology?Paul 5.Anticipated date?Henri 6.t values acceptable?Paul

2. Dendro Dating Artifacts Southwestern Ruins (~violins)

3. Grand SW Houses

4. A.E. Douglass Collected living- tree samples –Dated chronology Collected ruins samples –Undated chronology Connected the two

5. Dating Living back to ~AD 1250 700 year “floating” chronology Separated by a gap

6. Gap Piece Buried wood

7. The Bridging With skeleton plots No t values: who needs ‘em?

8. Raw width series not helpful for dating Yes: Trends look similar But: Most tree series have that trend Geometric constraint of tree growth

9. Detrended Series Standard series (blue) ok: –No trend –But has autocorrelation Residual series (red) even better, best –No trend –No autocorrelation

10. Autocorrelation a Bad Thing for Dating Undated tree sample with 290 rings Dated chronology with almost 600 rings “Significant” t values for 113 dating positions With residual series, only one dated position

11. ~ Standard deviation Difference of two rings divided by average Mean Sensitivity If two rings equal each other –Difference is 0 –Sensitivity  0 If one ring is 0: –Difference = average –Sensitivity  2

12. Messiah MS Quite low: –Residual series: 0.148 –SW chronologies  0.5 Stats dating of Messiah will be difficult Perhaps some other ring variable would be better, e.g., density

13. Question 3: What is the t value?

15. 2.5% t value is compared to Student’s distribution Large |t values| rare  significant

16. Adjusts correlation r values by sample size As r  0, t  0 As r , t  As r  1, t skyrockets t varies with sqrt(n) Famous t value Messiah has 109 rings Not bad, not great either

17. Multiple testing issue: –Do enough tests, you’re bound to get significant results Alpha level should be adjusted Standard stats As m , () , P  (penalty) t Value Penalty

18. Example: –500-yr chron –100-yr series –50-yr minimum overlap –500 tests Significant t value (p = 0.0005)  non- significance Worse with many chronologies t Value Penalty