Go back to what's in the article:

> To examine how this huge influx of workers affected the labour market in Miami, David Card compared the wage and employment trends in Miami with the evolution of wages and employment in four comparison cities.

> Despite the enormous increase in labour supply, Card found no negative effects for Miami residents with low levels of education. Wages did not fall and unemployment did not increase relative to the other cities. This study generated large amounts of new empirical work, and we now have a better understanding of the effects of immigration.

Look at the conclusion: "Card found NO negative effects for Miami residents with low levels of education." NO negative effects is quite the statement.

Now, the follow up studies:

> or example, follow-up studies have shown that increased immigration has a positive effect on income for many groups who were born in the country, while people who immigrated at an earlier time are negatively affected. One explanation for this is that the natives switch to jobs that require good native language skills, and where they do not have to compete with immigrants for jobs.

Now that's a negative effect. He made the assertion of NO negative effects.

In second year economics my prof would have failed me for such a basic conclusion. Look at influx of people, compare unemployment rates to other cities, make conclusion from that.

When immigration happens there's things happening on both sides of the supply/demand curve. Immigrants bring money, they also are labour. Different groups bring varying amounts of supply/demand. They compete for various jobs depending on their level of education (including language). There's also undocumented employment.

Anyhow, there's no mention of the wealth of the immigrants (often western nations are recipients of capital flight), no mention of aggregate demand, it says wages didn't fall but no mention of inflation and wage growth (ie. real wages), etc...

And if a study is so easily invalidated (sorry, elaborated upon), what's the point? Anyhow, it stuck out to me because it's an oft-cited study despite being incredibly basic and flawed (and many studies since more or less disproving it).

Anyhow, it's bad data (well, bad methodology from start to finish) because it draws a conclusion based on correlation between immigration and unemployment/wages without considering a ton of factors in between. It's like taking a chart of AAPL, GOOG, saying one depends on the other because they both go up during the same timeframe, ignoring everything else that's happening in the economy and tech industry.

Edit - it should also be mentioned, that literally the last ~5 or so years of politics in the west have centred around inequality, the plight of uneducated workers in the western world, globalism's effect of living conditions in the western world, etc... Populism on both the left and right is a thing because of it. It's pretty clear that a significant segment is being left behind. Wage stagnation IS a thing, and we know it because there's a lot of hindsight in the last 30 years. And Covid exacerbated inequality, with educated workers increasing their net worth drastically while lockdowns wreaked havoc on large segments of the economy. The cited study says absolutely nothing about the labour market, except that in one time and place, unemployment and wages didn't go down.