The Death Penalty or Life Meaning Life

[SadisticNature]

I have to take exception to the characterization above. Much of the support for the claim is the "fact: that a larger percentage of these people are actually in prison.

Perhaps that is because more crimes are actually committed by these groups.

Now I know I do not have data. While I was refilling my tea I thought about the data. It has to exist somewhere but I have to devlop the question to ask in order to find it.
I have to find data on arrests vs convictions somehow.

While you're at it you could try and find data on random stops. Police tend to be more suspicious of black people, so there are a far higher rate of random stops, and a far higher rate of searches at the border etc.

I have several acquaintances who smoke marijuana, 4 of whom took their personal amounts across the border, the three white guys weren't searched, the one minority was. Admittedly this is only an anecdotal case, but if stuff like this plays out in the larger data, then its quite likely blacks are not necessarily committing more crimes but rather are being treated with suspicion and hence are caught more frequently.

So looking it how arrests compare to convictions wouldn't show you the larger picture of what level of crimes are being committed. It would only show you what level of crimes are being caught. Assuming a random sampling is certainly problematic as there is strong evidence of bias. Take for instance racial profiling:

The idea behind it was that blacks committed a higher percentage of crimes, so if a police officer has two suspicious people (one white, one black) fleeing the scene of a crime and can only chase one of them they go after the black guy. There are several possibilities for what actually happened here:

Case (i): The black guy did it. They likely catch him and prosecute.

Case (ii): The white guy did it. He escapes the initial scene, and chances are somewhat poor that they track him down to catch him and prosecute.

Case (iii): They were accomplices. The black guy likely gets caught and is prosecuted. He may or may not turn over his accomplices.

So if you have a police force that responds to a chase scene in this way, you would have bias in your data. The white guy is far more likely to not be caught for this crime than the black guy.

[DuncanONeil]

While you're at it you could try and find data on random stops. Police tend to be more suspicious of black people, so there are a far higher rate of random stops, and a far higher rate of searches at the border etc.

You move from the general to the specific quite quickly here. You have referred to "assumptions", yet you are doing just that in the above statement. Said assumption being that police are intrinsically suspicious of black people. No one can provide empirical evidence that such is the case. Why does the border matter or is that meant to be a lead in to the following paragraph?

I have several acquaintances who smoke marijuana, 4 of whom took their personal amounts across the border, the three white guys weren't searched, the one minority was. Admittedly this is only an anecdotal case, but if stuff like this plays out in the larger data, then its quite likely blacks are not necessarily committing more crimes but rather are being treated with suspicion and hence are caught more frequently.

Yes it is anecdotal. And as previously stated there is no empirical data. If one of four, all guilty, were searched it seems reasonable to suggest there was some trigger, yes you would like to say color, it could be as simple as being nervous, or the manner in which questions are answered, or even a general manner of presentation.

So looking it how arrests compare to convictions wouldn't show you the larger picture of what level of crimes are being committed. It would only show you what level of crimes are being caught. Assuming a random sampling is certainly problematic as there is strong evidence of bias.

Not sure about the "level of crimes". That could mean nature or quantity. However with police located throughout the city there is no real reason to presume that criminals caught does not represent the set of criminals in general. Your issue of bias here is either poorly thought out or poorly stated. As written it presupposes a strong bias in any random sampling. In terms of the stats on crime we have at least three sets of data. Crimes committed, criminals arrested, and criminals convicted. Neither of these sets represents a random sample. They are the complete set!

Take for instance racial profiling:

The idea behind it was that blacks committed a higher percentage of crimes, so if a police officer has two suspicious people (one white, one black) fleeing the scene of a crime and can only chase one of them they go after the black guy. There are several possibilities for what actually happened here:

Case (i): The black guy did it. They likely catch him and prosecute.

Case (ii): The white guy did it. He escapes the initial scene, and chances are somewhat poor that they track him down to catch him and prosecute.

Case (iii): They were accomplices. The black guy likely gets caught and is prosecuted. He may or may not turn over his accomplices.

While the following are in fact my words they are a compiled sets of understanding of what you wrote. Happens that my daughter dropped by and read what you had to say in this scenario. Her opinion is that your entire scenario is biased.
She feels it is important to know what type of crime occurred. And further notes that in each case that you "assume" the black is the person chased.
In the description you have the officer presented with a crime scene with two people fleeing. That act by its nature makes both parties suspicious. In every point after that you "assume" the officer chases only the black. Can you not see that as a bias on your part. I know what I would do but, the officer on the scene is most likely to focus on the closer suspect than a specific factor of that suspect. Also in such situations decisions are made in a manner and speed that determination of why, can not be made, even well after the event. I have seen video of a person fleeing from the police make a high jump onto a wall that appears to be at least five feet high, sorry I am not going to try and chase him, no matter what he looks like.
It is so easy to dissect an officers actions after the fact. But such usually totally ignores the fact that every decision, in chases, must be made in fractions of seconds.

So if you have a police force that responds to a chase scene in this way, you would have bias in your data. The white guy is far more likely to not be caught for this crime than the black guy.

A police force responding to a chase does not respond with a single unit. Multiple units will automatically negate your "assumption" that only the black will be chased. Also every case you posit has the non black getting away. Not only from the scene but with the crime. You really think that an accomplice caught by the police is going to take all the blame on themselves and let someone else walk free?

[SadisticNature]

You move from the general to the specific quite quickly here. You have referred to "assumptions", yet you are doing just that in the above statement. Said assumption being that police are intrinsically suspicious of black people. No one can provide empirical evidence that such is the case. Why does the border matter or is that meant to be a lead in to the following paragraph?

Yes it is anecdotal. And as previously stated there is no empirical data. If one of four, all guilty, were searched it seems reasonable to suggest there was some trigger, yes you would like to say color, it could be as simple as being nervous, or the manner in which questions are answered, or even a general manner of presentation.


Not sure about the "level of crimes". That could mean nature or quantity. However with police located throughout the city there is no real reason to presume that criminals caught does not represent the set of criminals in general. Your issue of bias here is either poorly thought out or poorly stated. As written it presupposes a strong bias in any random sampling. In terms of the stats on crime we have at least three sets of data. Crimes committed, criminals arrested, and criminals convicted. Neither of these sets represents a random sample. They are the complete set!


While the following are in fact my words they are a compiled sets of understanding of what you wrote. Happens that my daughter dropped by and read what you had to say in this scenario. Her opinion is that your entire scenario is biased.
She feels it is important to know what type of crime occurred. And further notes that in each case that you "assume" the black is the person chased.
In the description you have the officer presented with a crime scene with two people fleeing. That act by its nature makes both parties suspicious. In every point after that you "assume" the officer chases only the black. Can you not see that as a bias on your part. I know what I would do but, the officer on the scene is most likely to focus on the closer suspect than a specific factor of that suspect. Also in such situations decisions are made in a manner and speed that determination of why, can not be made, even well after the event. I have seen video of a person fleeing from the police make a high jump onto a wall that appears to be at least five feet high, sorry I am not going to try and chase him, no matter what he looks like.
It is so easy to dissect an officers actions after the fact. But such usually totally ignores the fact that every decision, in chases, must be made in fractions of seconds.


A police force responding to a chase does not respond with a single unit. Multiple units will automatically negate your "assumption" that only the black will be chased. Also every case you posit has the non black getting away. Not only from the scene but with the crime. You really think that an accomplice caught by the police is going to take all the blame on themselves and let someone else walk free?

Your standards on data set here are the same standards that justified a lot of discriminatory laws, and pointed to studies that showed blacks were less intelligent then whites and hence needed to be treated differently, for their own good. The particular data in this case was data showing that blacks scored lower than whites on IQ tests. In fact this data was biased because it contained cultural references familiar to whites of the day but less common among blacks (in particular nursery rhymes). By accepting that data as accurate and using it to inform policy many problems were created.

Furthermore, my claims of potential for bias are based on a long history of bias and racial profiling in many police forces around the country. This was part of police culture for a long time, leading to riots in several cities and other such problems. I find it hard to believe that this behaviour vanishes the second we find it no longer appropriate. In my own city one of our former chiefs of police spoke out in favor of racial profiling, saying that it lead to more arrests and convictions. I don't have the data to dispute whether racial profiling leads to more arrests or convictions, but even assuming this claim is true, the fact is it leads to more arrests and convictions of non-whites.

So given that the police use methods (Racial Profiling for instance) that they argue are effective and result in higher arrest rates and higher conviction rates, but work against specific minorities, why should I believe the police have an equal chance of catching a white person as catching a black person if they both commit the same crime.

Even if racial profiling is not in use, this assumption could still be problematic.

Consider for instance a border security officer who processes vehicles. The person is required to search and suspicious vehicles. They happen to dislike rap music and think it is associated with gang activity, and hence search every vehicle of someone wearing rap attire.

To simplify the data lets assume that 40% of blacks are wearing rap related attire and 10% of whites are. Furthermore lets assume that an equal number of whites and blacks are carrying drugs across the border, and that the attire of the individual is independent of whether or not they carry drugs.

Over the long run this security officer will catch 4 black people for every white person even though they aren't being racist, and even though equal numbers of blacks and whites are committing crimes.

I'd argue the onus is on you to show the data actually shows what you claim it shows, given that I've presented both a plausible way in which the data can be inaccurate which you are unable to account for and a history showing that the bias has been present in the past.

The statement in your argument I have the most problem with is this: "However with police located throughout the city there is no real reason to presume that criminals caught does not represent the set of criminals in general.".

There are a lot of reasons to believe the set of criminals caught doesn't represent the set of criminals in general. For starters different types of crimes are caught at different rates, so if whites are committing more of a certain type of crime that gets caught less (say white collar crime) and blacks are committing one of the crimes (say armed robbery) that gets caught at a higher rate then there are problems in the data. Even if you focus in on a particular crime, you introduce all sorts of new biases, in particular the choice of crime to focus on (given that different crimes have different race data).

Lastly, even if you manage to reduce the data to a single crime without introducing bias, you still don't have evidence showing the arrest data mirrors the committed crimes set. Racial profiling is effective at catching criminals, but results in a higher rate of catching blacks than of catching whites. If police are using methods that are better at catching specific races then that introduces bias in the data. As argued above, they have historically used such methods so the onus is on you to prove they aren't using them anymore.

[DuncanONeil]

You make even less sense here than usual!You make an awful lot of assumption! then proceed as if they were fact!

Your standards on data set here are the same standards that justified a lot of discriminatory laws, and pointed to studies that showed blacks were less intelligent then whites and hence needed to be treated differently, for their own good. The particular data in this case was data showing that blacks scored lower than whites on IQ tests. In fact this data was biased because it contained cultural references familiar to whites of the day but less common among blacks (in particular nursery rhymes). By accepting that data as accurate and using it to inform policy many problems were created.

Furthermore, my claims of potential for bias are based on a long history of bias and racial profiling in many police forces around the country. This was part of police culture for a long time, leading to riots in several cities and other such problems. I find it hard to believe that this behaviour vanishes the second we find it no longer appropriate. In my own city one of our former chiefs of police spoke out in favor of racial profiling, saying that it lead to more arrests and convictions. I don't have the data to dispute whether racial profiling leads to more arrests or convictions, but even assuming this claim is true, the fact is it leads to more arrests and convictions of non-whites.

So given that the police use methods (Racial Profiling for instance) that they argue are effective and result in higher arrest rates and higher conviction rates, but work against specific minorities, why should I believe the police have an equal chance of catching a white person as catching a black person if they both commit the same crime.

Even if racial profiling is not in use, this assumption could still be problematic.

Consider for instance a border security officer who processes vehicles. The person is required to search and suspicious vehicles. They happen to dislike rap music and think it is associated with gang activity, and hence search every vehicle of someone wearing rap attire.

To simplify the data lets assume that 40% of blacks are wearing rap related attire and 10% of whites are. Furthermore lets assume that an equal number of whites and blacks are carrying drugs across the border, and that the attire of the individual is independent of whether or not they carry drugs.

Over the long run this security officer will catch 4 black people for every white person even though they aren't being racist, and even though equal numbers of blacks and whites are committing crimes.

I'd argue the onus is on you to show the data actually shows what you claim it shows, given that I've presented both a plausible way in which the data can be inaccurate which you are unable to account for and a history showing that the bias has been present in the past.

The statement in your argument I have the most problem with is this: "However with police located throughout the city there is no real reason to presume that criminals caught does not represent the set of criminals in general.".

There are a lot of reasons to believe the set of criminals caught doesn't represent the set of criminals in general. For starters different types of crimes are caught at different rates, so if whites are committing more of a certain type of crime that gets caught less (say white collar crime) and blacks are committing one of the crimes (say armed robbery) that gets caught at a higher rate then there are problems in the data. Even if you focus in on a particular crime, you introduce all sorts of new biases, in particular the choice of crime to focus on (given that different crimes have different race data).

Lastly, even if you manage to reduce the data to a single crime without introducing bias, you still don't have evidence showing the arrest data mirrors the committed crimes set. Racial profiling is effective at catching criminals, but results in a higher rate of catching blacks than of catching whites. If police are using methods that are better at catching specific races then that introduces bias in the data. As argued above, they have historically used such methods so the onus is on you to prove they aren't using them anymore.

[SadisticNature]

You make even less sense here than usual!You make an awful lot of assumption! then proceed as if they were fact!

I make specific assumptions to demonstrate one example. This is a common technique to show problems with data.

My point is not that the people are biased against rappers, and that leads to a higher conviction of blacks. My point is that if they were it could lead to biases in the data.

As for racial profiling itself it has been used for a long time. It is effective at catching people of certain races.

On what basis do you assume police have an equal chance of catching a culprit regardless of their race/background? To me that seems a massive unsupported assumption that you need to conclude that the arrest/conviction data reflect the crimes committed data.

[DuncanONeil]

Race, Crime and Justice in America
The Color of Crime
New Century Foundation
Oakton, VA 22124

Second, Expanded Edition
Major Findings
• Police and the justice system are not biased against minorities.
Crime Rates
• Blacks are seven times more likely than people of other races to commit murder,
and eight times more likely to commit robbery.
• When blacks commit crimes of violence, they are nearly three times more likely
than non-blacks to use a gun, and more than twice as likely to use a knife.
• Hispanics commit violent crimes at roughly three times the white rate, and
Asians commit violent crimes at about one quarter the white rate.
• The single best indicator of violent crime levels in an area is the percentage of
the population that is black and Hispanic.
Interracial Crime
• Of the nearly 770,000 violent interracial crimes committed every year involving
blacks and whites, blacks commit 85 percent and whites commit 15 percent.
• Blacks commit more violent crime against whites than against blacks. Fortyfive
percent of their victims are white, 43 percent are black, and 10 percent are
Hispanic. When whites commit violent crime, only three percent of their victims are
black.
• Blacks are an estimated 39 times more likely to commit a violent crime against
a white than vice versa, and 136 times more likely to commit robbery.
• Blacks are 2.25 times more likely to commit officially-designated hate crimes
against whites than vice versa.
Gangs
• Only 10 percent of youth gang members are white.
• Hispanics are 19 times more likely than whites to be members of youth gangs.
Blacks are 15 times more likely, and Asians are nine times more likely.
Incarceration
• Between 1980 and 2003 the US incarceration rate more than tripled, from 139
to 482 per 100,000, and the number of prisoners increased from 320,000 to 1.39
million.
• Blacks are seven times more likely to be in prison than whites. Hispanics are
three times more likely.
Just a beginning! The data supports the make up of prison population, however.

I make specific assumptions to demonstrate one example. This is a common technique to show problems with data.

My point is not that the people are biased against rappers, and that leads to a higher conviction of blacks. My point is that if they were it could lead to biases in the data.

As for racial profiling itself it has been used for a long time. It is effective at catching people of certain races.

On what basis do you assume police have an equal chance of catching a culprit regardless of their race/background? To me that seems a massive unsupported assumption that you need to conclude that the arrest/conviction data reflect the crimes committed data.

[DuncanONeil]

"Furthermore, my claims of potential for bias are based on a long history of bias and racial profiling in many police forces around the country."

Sorry but this statement makes an assumption and assumes it is correct within itself.

I make specific assumptions to demonstrate one example. This is a common technique to show problems with data.

My point is not that the people are biased against rappers, and that leads to a higher conviction of blacks. My point is that if they were it could lead to biases in the data.

As for racial profiling itself it has been used for a long time. It is effective at catching people of certain races.

On what basis do you assume police have an equal chance of catching a culprit regardless of their race/background? To me that seems a massive unsupported assumption that you need to conclude that the arrest/conviction data reflect the crimes committed data.

[DuncanONeil]

I have seen that three case senario here before. As to the data I was looking for I found some and am in the process of putting it in a form that willo be readable here. Some of the numbers may be surprising.
Still looking for convictions, think I have someplace to pick them out.

While you're at it you could try and find data on random stops. Police tend to be more suspicious of black people, so there are a far higher rate of random stops, and a far higher rate of searches at the border etc.

I have several acquaintances who smoke marijuana, 4 of whom took their personal amounts across the border, the three white guys weren't searched, the one minority was. Admittedly this is only an anecdotal case, but if stuff like this plays out in the larger data, then its quite likely blacks are not necessarily committing more crimes but rather are being treated with suspicion and hence are caught more frequently.

So looking it how arrests compare to convictions wouldn't show you the larger picture of what level of crimes are being committed. It would only show you what level of crimes are being caught. Assuming a random sampling is certainly problematic as there is strong evidence of bias. Take for instance racial profiling:

The idea behind it was that blacks committed a higher percentage of crimes, so if a police officer has two suspicious people (one white, one black) fleeing the scene of a crime and can only chase one of them they go after the black guy. There are several possibilities for what actually happened here:

Case (i): The black guy did it. They likely catch him and prosecute.

Case (ii): The white guy did it. He escapes the initial scene, and chances are somewhat poor that they track him down to catch him and prosecute.

Case (iii): They were accomplices. The black guy likely gets caught and is prosecuted. He may or may not turn over his accomplices.

So if you have a police force that responds to a chase scene in this way, you would have bias in your data. The white guy is far more likely to not be caught for this crime than the black guy.

[DuncanONeil]

Answer Part One
Sourcebook of criminal justice statistics Online
http://www.albany.edu/sourcebook/pdf/t412008.pdf

Table 4.1.2008

Estimated number of arrests a

By offense charged, United States, 2008

Offense charged
Total b 14,005,615

• Murder and nonnegligent manslaughter 12,955
• Forcible rape 22,584
• Robbery 129,403
• Aggravated assault 429,969
• Burglary 308,479
• Larceny-theft 1,266,706
• Motor vehicle theft 98,035
• Arson 14,125
• Violent crime c 594,911

aData are based on all reporting agencies and estimates for unreported areas.
bBecause of rounding, figures may not add to total. Total does not include suspicion.
cViolent crimes are offenses of murder and nonnegligent manslaughter, forcible rape, robbery,
and aggravated assault.
dProperty crimes are offenses of burglary, larceny-theft, motor vehicle theft, and arson.
Source: U.S. Department of Justice, Federal Bureau of Investigation, Crime in the United
States, 2008, Table 29 [Online]. Available: http://www.fbi.gov/ucr/cius2008/data/

While you're at it you could try and find data on random stops. Police tend to be more suspicious of black people, so there are a far higher rate of random stops, and a far higher rate of searches at the border etc.

I have several acquaintances who smoke marijuana, 4 of whom took their personal amounts across the border, the three white guys weren't searched, the one minority was. Admittedly this is only an anecdotal case, but if stuff like this plays out in the larger data, then its quite likely blacks are not necessarily committing more crimes but rather are being treated with suspicion and hence are caught more frequently.

So looking it how arrests compare to convictions wouldn't show you the larger picture of what level of crimes are being committed. It would only show you what level of crimes are being caught. Assuming a random sampling is certainly problematic as there is strong evidence of bias. Take for instance racial profiling:

The idea behind it was that blacks committed a higher percentage of crimes, so if a police officer has two suspicious people (one white, one black) fleeing the scene of a crime and can only chase one of them they go after the black guy. There are several possibilities for what actually happened here:

Case (i): The black guy did it. They likely catch him and prosecute.

Case (ii): The white guy did it. He escapes the initial scene, and chances are somewhat poor that they track him down to catch him and prosecute.

Case (iii): They were accomplices. The black guy likely gets caught and is prosecuted. He may or may not turn over his accomplices.

So if you have a police force that responds to a chase scene in this way, you would have bias in your data. The white guy is far more likely to not be caught for this crime than the black guy.

[DuncanONeil]

Answer Part Two
Total arrests
American
Indian or Asian or
Alaskan Pacific
Total White Black Native Islander

TTL 10662206 7382063 3015905 142908 121330


Murder 9859 4721 4935 99 104
Rape 16847 10990 5428 198 231
Robbery 100525 41962 56948 681 934
Assault 328736 208081 112325 4453 3877
Burglary 235407 157252 73960 2077 2118
theft 979145 666360 286844 12684 13257
GTA 74881 44674 28510 795 902
Arson 10734 8139 2331 132 132

Viole \b\ 455967 265754 179636 5431 5146
Prpty \c\ 1300167 876425 391645 15688 16409

Percentages to follow

While you're at it you could try and find data on random stops. Police tend to be more suspicious of black people, so there are a far higher rate of random stops, and a far higher rate of searches at the border etc.

I have several acquaintances who smoke marijuana, 4 of whom took their personal amounts across the border, the three white guys weren't searched, the one minority was. Admittedly this is only an anecdotal case, but if stuff like this plays out in the larger data, then its quite likely blacks are not necessarily committing more crimes but rather are being treated with suspicion and hence are caught more frequently.

So looking it how arrests compare to convictions wouldn't show you the larger picture of what level of crimes are being committed. It would only show you what level of crimes are being caught. Assuming a random sampling is certainly problematic as there is strong evidence of bias. Take for instance racial profiling:

The idea behind it was that blacks committed a higher percentage of crimes, so if a police officer has two suspicious people (one white, one black) fleeing the scene of a crime and can only chase one of them they go after the black guy. There are several possibilities for what actually happened here:

Case (i): The black guy did it. They likely catch him and prosecute.

Case (ii): The white guy did it. He escapes the initial scene, and chances are somewhat poor that they track him down to catch him and prosecute.

Case (iii): They were accomplices. The black guy likely gets caught and is prosecuted. He may or may not turn over his accomplices.

So if you have a police force that responds to a chase scene in this way, you would have bias in your data. The white guy is far more likely to not be caught for this crime than the black guy.

[DuncanONeil]

Answer Part Three
American
Indian or Asian or
Alaskan Pacific
Total White Black Native Islander

100.00% 69.20% 28.30% 1.30% 1.10%


Murder 100 47.9 50.1 1 1.1
Forcible rape 100 65.2 32.2 1.2 1.4
Robbery 100 41.7 56.7 0.7 0.9
Assault 100 63.3 34.2 1.4 1.2
Burglary 100 66.8 31.4 0.9 0.9
Larceny-theft 100 68.1 29.3 1.3 1.4
GTA 100 59.7 38.1 1.1 1.2
Arson 100 75.8 21.7 1.2 1.2

Violent crime\b\ 100 58.3 39.4 1.2 1.1
Property crime\c\ 100 67.4 30.1 1.2 1.3

\a\Because of rounding, percents may not add to total.
\b\Violent crimes are offenses of murder and nonnegligent manslaugh-
ter, forcible rape, robbery, and aggravated assault.
\c\Property crimes are offenses of burglary, larceny-theft, motor vehicle
theft, and arson.

While you're at it you could try and find data on random stops. Police tend to be more suspicious of black people, so there are a far higher rate of random stops, and a far higher rate of searches at the border etc.

I have several acquaintances who smoke marijuana, 4 of whom took their personal amounts across the border, the three white guys weren't searched, the one minority was. Admittedly this is only an anecdotal case, but if stuff like this plays out in the larger data, then its quite likely blacks are not necessarily committing more crimes but rather are being treated with suspicion and hence are caught more frequently.

So looking it how arrests compare to convictions wouldn't show you the larger picture of what level of crimes are being committed. It would only show you what level of crimes are being caught. Assuming a random sampling is certainly problematic as there is strong evidence of bias. Take for instance racial profiling:

The idea behind it was that blacks committed a higher percentage of crimes, so if a police officer has two suspicious people (one white, one black) fleeing the scene of a crime and can only chase one of them they go after the black guy. There are several possibilities for what actually happened here:

Case (i): The black guy did it. They likely catch him and prosecute.

Case (ii): The white guy did it. He escapes the initial scene, and chances are somewhat poor that they track him down to catch him and prosecute.

Case (iii): They were accomplices. The black guy likely gets caught and is prosecuted. He may or may not turn over his accomplices.

So if you have a police force that responds to a chase scene in this way, you would have bias in your data. The white guy is far more likely to not be caught for this crime than the black guy.

[DuncanONeil]

I suspect that data on so-called random stops would be next to impossible to produce short of actually getting the specific police logs or radio logs.

While you're at it you could try and find data on random stops. Police tend to be more suspicious of black people, so there are a far higher rate of random stops, and a far higher rate of searches at the border etc.

I have several acquaintances who smoke marijuana, 4 of whom took their personal amounts across the border, the three white guys weren't searched, the one minority was. Admittedly this is only an anecdotal case, but if stuff like this plays out in the larger data, then its quite likely blacks are not necessarily committing more crimes but rather are being treated with suspicion and hence are caught more frequently.

So looking it how arrests compare to convictions wouldn't show you the larger picture of what level of crimes are being committed. It would only show you what level of crimes are being caught. Assuming a random sampling is certainly problematic as there is strong evidence of bias. Take for instance racial profiling:

The idea behind it was that blacks committed a higher percentage of crimes, so if a police officer has two suspicious people (one white, one black) fleeing the scene of a crime and can only chase one of them they go after the black guy. There are several possibilities for what actually happened here:

Case (i): The black guy did it. They likely catch him and prosecute.

Case (ii): The white guy did it. He escapes the initial scene, and chances are somewhat poor that they track him down to catch him and prosecute.

Case (iii): They were accomplices. The black guy likely gets caught and is prosecuted. He may or may not turn over his accomplices.

So if you have a police force that responds to a chase scene in this way, you would have bias in your data. The white guy is far more likely to not be caught for this crime than the black guy.

[DuncanONeil]

This may also be of some interest.
http://www.albany.edu/sourcebook/pdf/t5572004.pdf

I suspect that data on so-called random stops would be next to impossible to produce short of actually getting the specific police logs or radio logs.