I think there is a large communication gap between us. I never claimed that all Black children misbehave.
When I say "men are taller than women", I am not saying all men are taller than all women (which of course, would be a ludicrous claim). It's merely a statement that men have a higher average height than women.
I know that. In fact, I can think of several field studies that could help to disentangle these questions, but they do not appear to have been done.
Examples: In some cultures, it is considered disrespectful for children and younger people to look adults directly in the eye. Yet, most white Americans perceive avoiding eye contact as a sign of deception and dishonesty. And judge accordingly. Which is one reason that Native American kids' suspension rates are so high relative to those of white students.
Students are suspended based upon a teacher's evaluation to a student's behavior. The teacher's evaluation will be influenced by the teacher's perceptions which is also influenced by the teachers' biases, conscious and unconscious.
There is also the fact that teachers and schools mete out discipline based partially on whether or not they feel they have good established relationship with the student's parents. If the teacher/school believes that a phone call to the parents will resolve the problem, discipline often stops there. Notice that this relies heavily on what the teacher/school believes to be true of the parents, not of the child and is not based on actual fact. A teacher may believe that a student who comes from a well educated white family who seems well engaged in the community has more supervision and the parents are heavily invested in the student behaving well/performing well. This may or may not be actually true. The parents may be very vested in appearances and may not actually spend any time with the kid. Contrast with another family who is multigenerational because grandparents and parents are all working and by living in a multigenerational home, the family may provide consistent discipline and supervision. But the school may simply perceive that family as being out of the mainstream, and 'unreliable' because the family doesn't fit a nuclear family 9-5 type of lifestyle. If you throw in perceived language barriers--the school may be inclined to skip the call to the parents and go to higher levels of discipline they would not with a student from the perceived 'ideal' family.
In science, an untested idea is called a hypothesis. If perceptions of family competency affect discipline choices, this is something you can test. You can also test at the same time if these perceptions are biased along race lines.
How does one go about designing such studies? How is data collected?
You'd probably look to the psychological literature for previous designs. A rating experiment would be useful -- videotape children (actors) behaving in a variety of different ways (physically violent, 'insubordination', etc) then get people (preferably child carers but let's face it it would probably be first year psychology students) to rate aspects of the behaviour on a behaviourally-anchored rating scale. The videos of course would have children of either gender and different ethnicities (including at least two children from each 'category') engaging in the 'same' behaviour, as much as practicable.
I would also like an observational study done (it could be done using historical data, if schools keep those records). For example, is there a detailed list of events for which children are suspended? Not the official, one-word reason (e.g. 'insubordination') but a detailed account (e.g. the student rolled their eyes at me and gestured rudely). The second one is not perfect because if White children are not being suspended for the same acts, they won't be in the records (unless they get a lesser punishment which is also recorded).