You can measure some crime without convictions. I.e. by ones being reported by crime's victims, or, in the case of homicide, by finding the victims murdered. Some crime like infamous "victimless" crimes can't be found this way, but my opinion is those probably shouldn't exist anyway as crimes.
His point is that being able to measure 'some' crime does not let you make statements about 'how much crime is committed by each race', just like being able to see the first row of trees in a forest does not let you make statements about how much of the forest is a particular kind of tree.
You can make statistical conclusions in some cases. I.e. if you take robberies, and you know that X% of robberies are commonly reported and you know that in Y% of robberies reported robbers were male, and you know that robberies committed by males and females reported with same frequency (note these are hypothetical assumptions, for the sake of example) - you can estimate how many robberies were committed by males, based on certain report statistics - not only on convictions. Of course, this would not be exact - statistics is not meant to be, the whole point is generalizing - but it would show the trends present in the data.
Right, but in this case, one of the points being questioned is whether we can assume that crimes committed by black people and non-black people are reported with the same frequency.
Why won't they be? Do you think somebody robbed by a white person would conceal this because they feel racial affinity to the robber? I have hard time imagining this. But of course real statistics would be helpful here.
They aren't even enforced consistently. Majority-white neighborhoods aren't policed the same way majority-black neighborhoods are.
Err, did you read the thread? We talked about reporting crimes, not policing neighborhoods.
I do not believe you could miss the connection.
This assumes that the reporting rate is the same for robberies committed by males and females. It is entirely possible that e.g. victims are less likely to report robberies commited by women. It's also possible that there is a bias in the reporting because victims tend to assume that robbers are male, even when the robber is masked and it's difficult to tell the gender of the robber.