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<p>[QUOTE=&quot;Roerbakmix, post: 3866936, member: 100731&quot;][USER=76086]@Ken Dorney[/USER] I&#039;m not quite sure I understand your histogram. What does the Y-axis represent? A cumulative revenue? There does seem to be a trend over time, but to sort of get a feeling whether there is a likely true increase/decrease compared to the previous month, statistical testing comes in place. If I understand it correctly, the Y-axis is a mean (?) of a couple of (?) years (?). If so, a simple T-test would suffice to get a general feeling. If you&#039;re comfortable enough in providing the data, I can do this.</p><p><br /></p><p>[USER=75525]@rrdenarius[/USER]: you&#039;re probably completely right: the number of bidders is likely to say something about the hammer price. I do not have this variable however. In my experience, it is only visible <i>during</i> the auction, and not after the auction. If looking at causality (I&#039;ve tried four case studies so far: the two being shown here (JC denarius; Augustus divus Caesar denarius), a medieval Anglo-Saxon penny, and the Attica Tetradrachm), there certainly is a very strong significant relation between grade and estimate, even when corrected for other variables such as toning y/n, damaged y/n, provenance, etc. This is to be expected of course, as I&#039;ve explained above.</p><p><br /></p><p>[USER=46237]@Jaelus[/USER] it would probably be a fun exercise to compare estimate vs hammered of each auction house and add this as a weight to the model. I&#039;ll consider it, but it&#039;s of course a lot of work and the estimate will probably not be very precise. Still fun to consider.</p><p><br /></p><p>For those still following the thread, I&#039;m trying a couple of things:</p><p>1) predicting the hammer price (i.e. the price a coin will sell for) given various variables</p><p>2) establishing a relation between these variables and the hammer price</p><p><br /></p><p>Please note that in model 1 (prediction model) a non-causal relation is implied, while in model 2 (aetiological model) an causal relation is implied. </p><p><br /></p><p>For this, I am looking for information that might be related to the hammer price. So far, I&#039;ve got this:</p><p>- estimated price</p><p>- grade </p><p>- provenance</p><p>- NGC or other </p><p>- broken / damaged / off center / repaired / scratched, etc. </p><p>- bankers mark</p><p>- month of the year</p><p>- (auction house might be a possibility, but is difficult due to the number of auction houses per given coin and thus the required flexibility of the data for that number of degrees of freedom). </p><p><br /></p><p><b>Do you have other possible predictors? </b>[/QUOTE]</p><p><br /></p>

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