ex-post
Ex Post means looking at what actually happened after the fact, using real figures rather than forecasts or plans.
In plain English
Why did your December business projections look nothing like what actually landed in your account by January? That gap between the plan and the reality is exactly what ex post helps explain, because it deals only with what has already happened, not what you hoped would happen.
In economics, there are two ways to look at any number. Ex ante means before the fact, the forecast, the budget, the plan you drew up in your head or on paper. Ex post means after the fact, the actual result once the dust has settled and the books are closed.
Say a trader in Onitsha plans to make ₦2,000,000 profit this quarter, that is her ex ante figure, the one she is hoping for. At the end of the quarter, she counts her actual sales, subtracts real costs, and finds she made ₦1,300,000. That final number, the one drawn from what truly occurred, is her ex post profit.
Governments and central banks use this idea constantly. The Central Bank of Nigeria might forecast inflation at 20 percent for the year, that is ex ante. Once the year ends and the National Bureau of Statistics releases the real figures, whatever inflation turns out to be, that is the ex post number, and it is the one that actually affects prices in the market and the value of the money in your pocket.
For someone in London sending money home every month, this matters more than it seems. You might plan, ex ante, to send £200 assuming a certain exchange rate. By the time the transfer lands and converts, the actual rate, the ex post rate, may have shifted, and your family receives more or less than you both expected.
Economists lean on ex post data because plans can be wrong in a thousand small ways, but what actually happened is what actually happened. It is the receipt after the promise, the truth after the guess.
A Lagos landlord budgets ex ante for ₦500,000 in annual repairs on a property. By year end, actual repair costs, the ex post figure, come to ₦680,000 because of unexpected plumbing work, showing why relying only on the plan can leave you short.
Questions people ask
What is the difference between ex ante and ex post?
Ex ante is a figure calculated before an event, based on forecasts or plans. Ex post is calculated after the event, using the actual outcome. Ex ante inflation is a prediction, ex post inflation is what the data later confirms actually happened.
Why does ex post data matter for ordinary people, more than economists?
Because your household budget, your business projections, and even remittance amounts are ex ante guesses. Comparing them against ex post reality helps you spot where your assumptions were off, so your next plan can be more accurate.
Can ex post figures be revised later?
Yes, sometimes an initial ex post figure, like a quarterly GDP number, gets revised once more complete data comes in. It is still ex post, just a more refined version of the actual outcome, rather than a forecast.
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