Originally Posted by Kosty
Well its been a lot closer since Aug 2012 between the HMM and The-Numbers marketshares so using the DVD estimates against the NV unit percentages will give about same result as their Blu-ray estimates.
By all reports since last fall the Walmart BD share of the market since the 4Q 2011 period is now close to their 40% traditional DVD share so for most genres the reported Nielsen Videoscan first alert numbers will be closer now to the truer Blu-ray share for the entire market.
In the summer period you also are looking that above that's also a lower volume time so the percentage variation will equate into a smaller absolute unit magnitude variation as well. Then of course they are just estimates as well for any title each week and expected to be 5% to 10% accurate so that sort of variation would not be surprising. If anything the current close match between the The-Numbers and Nielsen Videoscan Blu-ray unit marketshares since August 2011 is almost too close.
If the question was the 4Q 2011 and 1Q 2011 and 2Q 2011 or earlier calculations using that method its clear that the The-Numbers ratios that were supposed to include Walmart in the consideration should be lower than the Nielsen Videoscan percentages that did not include Walmart in the Nielsen Videoscan first alert point of sale census. That's exactly what you should expect, the figures that include Walmart should have a lower Blu-ray unit revenue share than the figures that did not consider Walmart.
It been a lot closer lately, but last January is not "lately". The-Numbers didn't start tracking Blu-ray until May, and when they did, their Blu-ray shares were smaller. Around an average of 15-20% smaller. That time period is much closer to last January than "lately", and as such, if any assumption is to be made, it should account for this prevailing discount factor.
For example, for the week ending May 8th, The-Numbers DVD figures for The Green Hornet is 449,314. The Nielsen Blu-ray share is 49.5%, which would calculate to 440,416 Blu-ray units.
However, The-Numbers reported the Blu-ray units for this title to be only 291,320 units. That's a whopping 33.7% less than just by plugging in Nielsen ratios into DVD units.
And the funny thing is, after you make that 33.7% downwards adjustment on that title, for that week, the rest of the titles generally fall into the same ratio adjustment, give or take a few percent.
Bottom line, don't use DVD units with Nielsen Blu-ray share to get Blu-ray units. Actually, I don't like to use The-Numbers data on anything, because their data has been proven to be too unreliable. However it can be of use when comparing two different apples to apples periods, such as top 10 Blu-ray May 8th 2012 vs. 2011. Or finding how certain titles attrition over the first few weeks. But NOT using DVD numbers with Blu-ray ratios from a different source to get Blu-ray numbers. Please.