It helps to link to articles that you're (probably) talking about:
It’s hard to put a number on it. For one thing there’s no agreed definition of a world recession. According to a rule sometimes used by the IMF, a world recession is when the global growth rate is less than 2.5 percent. Global growth doesn’t turn negative often. It happened in the global ...
NOTE: the question has been modified to refer to a global recession (or I missed the global qualifier). This answer is for a national recession. The answer by @Fizz discusses the global case. I will leave my answer unchanged.
There is no international standard for a recession definition. Definitions are country-specific. For example, in the United States, ...
The BEA does use the generic growth formula to calculate percent change of GDP.
The formula used by BEA to calculate the average annual growth is a variant of the compound interest formula:
Formula used by BEA to calculate the average annual growth.
GDPt is the level of activity in the later period;
GDP0 is the level of activity in the ...
Normally growth is calculated either as:
Or approximated by:
Within year you can either continue using the above definition or use year on year growth which compares every month quarter with the same quarter previous year.
If you are looking for Fred specifically here is the list of formulas:
That quote from Wikipedia page is not correct. Actually both OECD and also commonly in economic research we define potential GDP/output as:
Potential gross domestic product (GDP) is defined in the OECD’s Economic Outlook publication as the level of output that an economy can produce at a constant inflation rate. Although an economy can temporarily produce ...