Tag Archives: REDFIT

Lasers, biomarkers and the Sun

Posted on 04/11/2014 by richard telford

The earliest work on Holocene palaeoecology focused on megafossils such as Pinus stumps. Then macrofossils such as hazel shells were used to reconstruct species distributions and climate. Then pollen analysis became important, complementing rather than supplanting the larger fossils. The end of this progress towards smaller … Continue reading →

Posted in climate, Novel proxies, Peer reviewed literature, solar variability | Tagged , , | 1 Comment

Sun-kissed Skeletonema costatum? Patterson et al (2013)

Posted on 11/09/2013 by richard telford

This is part of my critical review of the palaeoenvironmental evidence for the influence of solar activity on climate. Patterson et al (2013) have a new paper that reports evidence of the 11-year sunspot cycle on diatoms and sediment characteristics in a … Continue reading →

Posted in climate, Peer reviewed literature, solar variability | Tagged , , , | 1 Comment

REDFIT’s rule of thumb

Posted on 07/08/2013 by richard telford

Because REDFIT tests many frequencies, some are likely to appear statistically significant just by chance — a classic multiple testing problem.  Schulz & Mudelsee (2002) “follow Thomson (1990) and select a false-alarm level of (1-1/n)*100%, where n is the number of data points … Continue reading →

Posted in EDA, Peer reviewed literature, R | Tagged , | 1 Comment

REDFIT & false alarms

Posted on 06/08/2013 by richard telford

REDFIT is a useful tool for palaeoecologists who like to test their data for periodicities as it uses the Lomb-Scargle Fourier transform which tolerates unequal time intervals and so avoids the problems inherent in interpolating data to equal intervals. Several of the papers reporting the … Continue reading →

Posted in EDA, Peer reviewed literature, R | Tagged , | 3 Comments