There is no simple way to tell how well a country is doing economically. Economies are commonly ranked in terms of gross domestic product (GDP) and we then say that the US comes first, China second and so on. However, GDP is simply a measure of money changing hands which tells us nothing about whether it is changing hands wisely, profitably or productively. A country could have a high GDP because it is spending vast amounts on overseas wars and bankrupting itself in the process. On the other side, a civilised country may be one in which many benefits flow without any movement of cash at all. A public space with no entry fee does not contribute to GDP, but if it is fenced off and a casino built on the same piece of land this shows as a big step forward. Different countries have different value systems and this distorts the measure of economic value too. A country where what is sought is short term profit ("a quick buck") is likely to appear to be a more dynamic, productive land than one where people are prudent and take a longer term view. Again, any efficiency introduced into an economic system has a short term effect of increasing unemployment and diminishing GDP. In the longer term, however, one sees something different.
A classic example is the way that the euro rapidly lost value when it was first introduced. Euro-sceptic commentators took this as a sign that the euro was a failure. However, it actually demonstrated exactly the opposite. The exchange value fell because the euro was more efficient than the currencies it replaced, hence one did not need so many of them to do the same job. When you have more than you need of something, its price falls.
Values in money terms tell nothing about what the money is being used for. In terms of GDP, the UK is the fifth largest economy in the world (after USA, China, Japan and Germany). However, about three quarters of the UK GDP is generated by "financial services". The city of London is insurer to much of the rest of the world. This is a rather vulnerable position - to have so many eggs in one basket. Russia, for instance, is generally thought to need to achieve a more balanced economy but it is much less unbalanced than the UK. Although the Russian economy is only half the size of that of the UK in terms of GDP, Russia is probably capable of withstanding hard shocks better - indeed is already doing so. This is in part because much of Russian life does not depend upon the commercial market to anything like the extent that life in UK does.
Then, of course, when you put a price on something that price has to be denominated in something else that also fluctuates in value. Thus, at the end of 2016 there were headlines saying that the London Stock Exchange was at a record high level. This was true measured in pounds sterling. Compared with one year earlier, the LSE was up. However, during that year, due to the Brexit vote, the value of sterling itself had fallen by about 15% in terms of the dollar and euro. In international terms the value of the LSE was almost exactly the same at the end of the year as it had been at the beginning. In other words, the stocks were still what they had been, it was the money that was worth less.
This sort of thing is a major problem for democracy. Political decisions are often, essentially, economic decisions and in many cases the general public has no real idea of cause and effect or even of the meaning of such figures as are available. It is difficult even for experts to really know the true situation.
Replies
For instance, China
China is in the news today for saying that its estimate of GDP growth for the coming year will be 6.5% which is less than previous years. On GDP, China is the second largest economy in the world. On the IMF’s “purchasing power parity” score it is the largest in the world. On a per capita income basis however it is 72nd. It is the biggest manufacturer of tangible goods and the biggest trader in goods, but is far behind on services. Again, China has seen rapid GDP growth but much of it has been financed by borrowing. We could all spend more if we borrow more but does this actually make us better off, especially when we have to pay the interest? On the other hand, China has loaned a lot of money to the USA. This is partly for economic reasons - the US likes to overspend too, and this lending keeps Chinese good relatively cheaper than American ones (something that exercises President Trump - but then Americans like to be able to buy the cheap Chinese goods), but also political ones (China always has the threat to sell all is American dollars thus causing the value of the dollar to fall against the euro and yen which is something the US has to worry about). So is China doing well or badly? Only time will tell.