Explanation concerning the Modal Roger1 chart

We've computed Modal Roger1, our determination of Roger1's yDNA to 111 markers, in a two step process, since we want to avoid giving extra weight to any of his sons' lines. So we first compute Modal John2, Modal Samuel2, Modal Roger2, Modal Thomas2, and Modal Daniel2, and then use them as input to compute Modal Roger1. (Note that what is presented on the chart is not a complete presentation of all the steps involved. It would take a fuller chart to present everything.) In every case a result is computed for each marker—the mode of the input marker values for that marker in that column (say, descendants of John2). Note that a mode (a most frequent value) cannot always be defined. For instance, the mode of 11 and 12 is undefined (so call it '?'). However, a mode can be defined even if one of the input values is undefined. For instance, the mode of 11, ? and 11 is 11. So, Modal Roger1 can be completely determined even if Modal John2, Modal Samuel2, Modal Roger2, Modal Thomas2, or Modal Daniel2 were not completely determined.

We descendants of Roger1 did not just happen to luck out in being able to determine Modal Roger1 so completely—it's a consequence of the rarity of mutations. Knowing Modal Roger1 we can now go back and eliminate question marks in some, but not necessarily all, of the contributing components. This may not be clear to you. Prior to the era of data privacy we were able to explain things in detail using actual marker values; but even then the chart changed so often that the explanation soon became outdated. Perhaps you can just take our word for it that we are being as careful as possible in processing the data.