For the purposes of calculating statistics, the artworks are assigned to a media classification.  (See the FAQ on media classifications for more information).  For each of these media classifications, and for each calendar year, we calculate the following metrics:

Qty - The number of artworks of that medium that were sold during the year.  Note that it includes sold artworks only, and not artworks that were passed in.  Clicking on the number will link to the actual artwork records.

Mean - The average (mean) price of artworks sold during the year.  This is calculated by dividing the sum of the realised prices of artworks sold by the quantity sold (see above).

Mean price per sqcm - Rather than the mean price per artwork (as per above), this represents the mean price as a figure per square centimeter.  This reduces, to some extent,  the effect of the variable of size.

Mean Size (sqcm) - This is the average size of artworks sold of that medium during the year, represented as the average square centimeters per artwork. 


Interpreting the results
Ideally, the metrics above should be looked at together, because looking at only one metric may be deceptive.  For example, when looking at the mean prices you should also look at the quantity sold.  Were there enough sales in the year for the mean prices to be statistically reliable?  If there were only a few sales in one year, and those artworks sold were created during an artists highly acclaimed and sought after period, it may not be accurate to compare this to a different year where there were a high number of sales of varying quality.  This is why the artworks used in the calculations can be viewed by clicking on the quantitly link (the number highlighted in red). 

The Mean Size (sqcm) metric can be used to provide further context to the Mean price per sqcm.   For example, lets say that oil paintings for an artist during 2006 achieved a Mean price per sqcm of $1.20, and in 2007 this changed to $1.00.  By looking only at this metric, it would appear that this artist's oil paintings have lost some appeal.  However, if we also look at the Mean Size (sqcm), we can see that this was 160sqcm in 2006 and 220sqcm in 2007.  Generally, given all other things being equal, although a larger painting will command a higher price, it will have a lower price per sqcm.  So in this example, it may be that the larger sizes of the paintings in 2007 contirbuted to the lower Mean price per sqcm.  There are ways to adjust the statistics to completely remove the impact of the variable of size, and we will be looking at introducing this in the future.

Of course, the statistics do not take into account the quality of a painting.  This is why we link to the actual artwork records (click on the red number in the Qty metric), so that you can get an idea of the quality of the paintings used in each metric.