In my multicultural ed class I've learned that race and intelligence are not correlated. Rather there are other factors that influence socio-economic success.
Are we talking about the success of various races of people residing in the US? Keep in mind that English is the predominant language in the US and is essential for success in the workplace. Many immigrants who come to the US struggle with acquiring proficiency in English. This can make it tougher to get a job that pays a decent salary.
Last year, I taught English and Reading in Middle School. One afternoon, i was doing some work at my desk when a female Hispanic janitor came into my room to take the trash out and sweep the floor. She asked me what I teach and I was surprised to know that she knew a great deal about classic literature/authors. I was surprised at how well she spoke English. She was practically fluent in English compared to many of the other janitors who had trouble even forming a sentence. And there was an air of confidence about her that set her apart from the other workers. She told me that in her native country she was a professor.....and had a high degree (Masters, PHD, can't remember)......and she taught either math or science at the university level........and that she had even taught in foreign countries (in Africa somewhere?). It was a long time ago and the details are blurry. But she told me that it was tough for her to find a job here because the educational credits in her country don't match up with the educational standards in the US.
^Perhaps this lady was exaggerating, but based on her style of speaking and manner....I doubt it. Often times, even doctors who have received their education in Pakistan.....struggle in getting a job in their field of specialization in the US because there is a disparity between the educational standards/credits. I've known some doctors from Pak who have successfully completed their medical education and training in their native country and had to work delivering pizzas for quite some time until they were able to "make it" here. We've all heard the saying that "the immigrants are stealing American jobs." That's actually a myth. The reality is that many immigrants hold menial jobs that pay low wages (janitorial work, cashier, construction worker, etc) that **FEW **people from among the predominant population (White/Caucasian) would want themselves. But somebody has got to keep the floors and streets clean........and these jobs also contribute toward the overall economy.
As far as the African American culture is concerned.........many of them live either at or below the poverty line. I once read some research stating that the usual case is that people tend to stay within their socioeconomic class. In other words if you were born and raised in the middle class......chances are that you will stay in the middle class. Of course there are exceptions. But for those minorities who are living in poverty, they often times have trouble affording the basic necessities for survival (medical care, food, etc).....let alone the secondary luxuries of life. The divorce rate tends to be higher in these situations. Children are being raised by single parents who are working two jobs to make ends meet......and they are not around to supervise their children and make sure that the homework is getting done or that their children even have basic school supplies such as paper and pencils. Substance abuse (alcohol and drugs), high crime rate, and teenage pregnancies are also prevalent among minorities from the lower socio-economic class. And these issues get in the way of economic success.
Attitudes: Play a role as well. Some (not all African Americans).....feel that that if an individual from their race advances professionally........that such an individual has forgotten his roots and decided to become "WHITE." Such an attitude is very damaging not only for oneself but for the community on a whole. While discrimination in the workplace has been greatly reduced (compared to how things were decades ago).....we're not totally clear yet.....and that would be an impossible feat to accomplish anyways. I learned in one of my classes that according to some research........employers are less likely to call a candidate who has a "Black" sounding name for an Interview.
Also, it depends on which occupational fields the various races are more drawn toward. There is a greater emphasis on education (in general) within in the Asian community. At least in the US.......there are welfare programs and other financial assistance programs that are available to those who are struggling financially. In countries like Pakistan and India.............there are very few financial programs available for the poor. Perhaps that is one reason why desi parents (even back in Pakistan) place a stronger emphasis on education and becoming a "doctor or engineer" for their children............because they know that in their own country they don't have assistance organizations and programs to fall back on.