There's lots of good arguments being made both for and against ioi's theories. I also appreciate the effort that ioi puts into making all this happen, but my personal opinion is that his effort is wasted because of the inaccuracy of the data. This may be a clever way to avoid copyright issues, since his data doesn't match any of the research groups', but that's not my concern.
The main cause of inaccuracy is the theory that shipped = sold. This is surely true for a number of games, but it is also totally untrue for a number of other games. I'll show two opposite examples to make my point. One is the successful game with long legs that hangs around the bottom half of the top 50 for a few years. Shipped =/= sold in this case, because stores have a large amount of stock of said game. When the game does eventually stop selling, the stock remains in stores. You can go into a store in Japan and find multiple copies of games like Super Mario Sunshine, Super Smash Bros., Final Fantasy X, Dragon Quest VIII.
The second example is the failure. Lots of orders are made by stores, lots of copies are pressed, and right now, the unsold software is sitting in storage somewhere, waiting to be either sold off at ridiculously cheap prices some day in the future, or disposed of entirely. If a 7000 yen game is sold off for 500 yen to get rid of stock, should its sales be counted at the same rate as a full price game? The research groups can't really track this data, as it's spurious, so it's not covered anyway, but equating shipped with sold will include junk like this, which demeans the value of the data.
With these points made, I focus again on ioi's data. He has stated himself, that his figures are an average of the different research groups'
adjusted to be closer to shipment figures. This "adjustment" may work for companies that supply their shipment figures, but for those that don't, this "adjustment" is nothing more than a blind assumption. Not only is this adjustment based on an idea that is incorrect (that sales = shipments), but it's being applied uniform across the board for games that he doesn't have shipment data for.
The people who don't put faith in ioi's data, the people who like to follow Media Create, or Enterbrain, or MediaWorks data do so because it is a single path of accuracy - any errors Media Create or whoever will make, will be relative only to that path, and can be spotted when compared with other researchers. Significant figures are counted because we like the only data source we have to be as accurate as possible. Get sloppy and mistakes multiply, making bigger discrepancies in the data.
I personally just feel that ioi's efforts would be so much more useful if he actually directed them towards accuracy. As it stands now, ioi makes his own numbers using his own theories and they cannot be relied upon. The DS life to date thread showed that even using his 5%+ mechanism, some of his data is still less than Media Create has on file. This is even after he's included his "adjustment" to bring sales closer to shipments. How can the data be relied upon when discrepancies like this occur. He just has no way to track sales of games when they've fallen from the charts, so the adjustment is not compensating correctly. People who follow the raw data from Media Create simply wait until we have an opportunity to see the current data, rather than making blind assumptions.
Long post, I know. I just felt like clarifying my stance on ioi's work.
His self-promotion is another thing entirely
