Net Results:How important are immigrants to creating wealth? One word: vital. A groundbreaking new study from the National Venture Capital Association in the US reveals just how vital - to the tune of hundreds of billions of dollars and hundreds of thousands of jobs.

One out of every four public, venture-backed companies founded since 1990 in the US has at least one immigrant founder, according to the report. And these companies, among them Sun Microsystems, Yahoo, eBay, Google and Intel, have a collective market capitalisation of an extraordinary $500 billion (€390 billion) and are responsible for 400,000 jobs globally (including thousands in Ireland).

Within the technology sector, that immigrant figure rises to 40 per cent. Yes, you read that right. An immigrant helped found two in every five technology companies in the US. Some 87 per cent of all immigrant founders are in three sectors central to a knowledge economy: information technology; life sciences and high-tech manufacturing. They come predominantly from countries like India and China, the Middle East and Taiwan.

Now think of whether those sectors, and the phrase "knowledge economy", has any relevance for Ireland. Hold that thought.

For now, back to the report. Look at the list of private, venture-funded companies right now in the US, notes the report, and the figures are even larger. Almost half - some 47 per cent - of all current venture-backed start-ups in the US have an immigrant founder.

Almost half of all the immigrant entrepreneurs, 46 per cent, arrived as students. More than half of the founders started their businesses within 12 years of entering the US. They hold an average of 14.5 patents. Two-thirds of them say they are going to start more US-based companies. Most become US citizens.

But two-thirds of immigrant entrepreneurs surveyed for the report state that current US immigration policy is having a negative affect on the workplace and on entrepreneurship. In particular, they are concerned about the US working visa scheme, noting there aren't enough visas available for immigrant workers needed to fill jobs, which means companies either lack the workers they need, or in the case of larger firms, outsource jobs abroad to take the jobs to the workers.

Obviously, outsourcing removes a whole net of taxpayers from the US system as well as a whole skills base. More importantly, the increasing move to close down the doors to immigration in the US prevents the people coming in - as students, as workers, as spouses - who themselves, or whose children or children's children, become tomorrow's entrepreneurs.

The report says: "Few of the immigrant entrepreneurs identified came to America ready to start a company capable of attracting venture capital. As the data, profiles, and interviews revealed, most entered the country either as children, teenagers, or graduate students, or were hired on H-1B visas to begin a first job while in their mid-twenties."

One of the authors of the study, Stuart Anderson, told the tech entrepreneur online network, AlwaysOn.com: "A key lesson of the study is the importance of maintaining a more open, legal immigration system. Few of these impressive immigrant entrepreneurs could have started a company immediately upon arriving in the US." And Jerry Yang, one of the two co-founders of Yahoo, said: "Yahoo would not be an American company today if the US had not welcomed my family and me almost 30 years ago. We must do all that we can to ensure that the door is open for the next generation of top entrepreneurs, engineers and scientists from around the world to come to the US and thrive. Whether they arrive as children, students, or professionals, we want the best and the brightest here.

"Our immigration policy should reflect that or these talents will go elsewhere."

This is such a crucial point, and has such great significance for Ireland, its total focus on growing a knowledge-based economy, its huge reliance on the information technology, high-tech manufacturing, and life sciences sectors, and its thus far tepid, timid and dangerously cautious approach to bringing in immigrants, especially within the technology sector. And its view that there are "good" immigrants ready to step into already-offered jobs, and "bad" immigrants, who aren't, goes directly against the US experience of immigrant entrepreneurship.

It has taken years of arguing by companies, IDA Ireland, and industry associations like the Irish Software Association and IT Ireland to get the Government to create a cautious work visa programme whose base salary is still so high that it only allows companies to bring in higher end workers, not those badly needed to fill average engineering and computing jobs. Or to give companies a little bit of scope to hang on to at least some of their bright postgraduate researchers from abroad. Or to enable foreign students who completed degrees here to stay on and work here.

These are small and inadequate steps and ignore the message this study so obviously conveys on how central immigrants are to the creation of wealth and economic vitality.

Talk to technology companies large and small, universities and technical colleges, and immigrants themselves, and the picture is, worryingly, like the one reflected with great concern in this US study.

Our narrow-minded immigration policies and the refusal to see the big immigration picture at every level throttles Ireland's ability to compete and innovate. The failure to bring in long promised school programmes designed to deter racism and eradicate stereotypes. The failure to educate the public about who immigrants are, why they come here, what they want to do, what their own cultures are like. The disgusting failure of the majority of politicians to touch the immigrant issue in their own regions for fear of losing votes. The continued silent tolerance of intolerance.

If immigrants are so important, at the very high end level of company creation, to the enormous US economy, then only think how important they already are, and are going to be to our economic future, in our very small economy.

There isn't a politician in this country who should not download this report and think about the consequences of continuing the way we are now.

American Made: the Impact of Immigrant Entrepreneurs and Professionals on US Competitiveness: www.nvca.org/pdf/ AmericanMade_study.pdf