Deflation vs Disinflation
Deflation and Disinflation are two Unemployment & Inflation concepts in AP Economics that students often mix up. Deflation is a sustained fall in the general price level of an economy, measured as a negative annual percent change in a price index such as the CPI. Disinflation is a fall in the rate of inflation while prices are still rising, so the price level keeps increasing but more slowly than before. Here is how they compare side by side.
Deflation is a rare and unusual economic phenomenon where there is a sustained decrease in the general price level of goods and services in an economy over a period of time. It is measured as an annual percentage decrease in the CPI. Deflation can be caused by various factors, including a decrease in the money supply, a decrease in aggregate demand, and improvements in productivity. Deflation can have negative effects on the economy, such as reducing spending and investment, and increasing the burden of debt.
Disinflation occurs when the rate of inflation decreases over time, but prices are still rising. It is a situation where the inflation rate is slowing down, but not yet negative. Disinflation can be caused by various factors, including a decrease in aggregate demand, an increase in productivity, and a decrease in the money supply. Disinflation is often seen as a positive development, as it can help to reduce the cost of living and increase the purchasing power of consumers.
Deflation vs Disinflation: Is the Price Level Falling, or Just the Inflation Rate?
| Deflation | Disinflation | |
|---|---|---|
| Sign of the inflation rate | Negative, so the index reading itself falls | Positive but smaller than last period, so the index still climbs |
| Effect on a fixed nominal debt | The real burden rises, borrowers lose ground | The real burden still shrinks, only more slowly |
| Usual cause | A deep recessionary gap or a large leftward shift in AD | Deliberate tightening, or a favorable supply shock |
| Is it ever the aim of policy | No, a central bank fights it rather than seeks it | Yes, it is what a central bank is buying when it tightens |
| What blocks the fix | Nominal rates stall near zero, so the real rate cannot be pushed down | Nothing structural, the bank can stop tightening whenever it chooses |
| Phillips curve reading | The point sits below the zero line on the inflation axis | A move down and to the right along the short-run curve, still above zero |
| Effect on real wages when nominal wages are sticky | Real wages rise as prices fall, which widens the gap | Real wage growth merely slows, no nominal cut is needed |
Run a price index through both and the ambiguity disappears
Take a hypothetical consumer price index that reads 100 in Year 1. Inflation of 6 percent brings it to 106 in Year 2. Inflation of 4 percent brings it to 110.2 in Year 3. Inflation of 2 percent brings it to 112.4 in Year 4. Across that whole stretch the economy experienced disinflation, because the rate fell from 6 to 4 to 2, and yet the basket cost more in every single period. A shopper in Year 4 pays about 12 percent more than a shopper in Year 1. Now suppose Year 5 records inflation of negative 1 percent. The index falls to 111.3. Only in that final period did the economy experience deflation, and only then did the basket actually get cheaper. The test is the sign of the inflation rate, not the direction the rate is moving. Disinflation is a shrinking increase in the price level. Deflation is a falling price level.
Both punish borrowers through the same channel, and deflation just pushes it further
Suppose a borrower signs a loan at a nominal rate of 7 percent when everyone expects inflation of 5 percent. The expected real rate is 2 percent. If disinflation drags actual inflation down to 2 percent, the realized real rate is 5 percent, and the borrower repays in dollars worth far more than anticipated while the lender gains. Now push the same economy to deflation of negative 1 percent. The realized real rate on that fixed loan becomes 8 percent. Nothing about the mechanism changed, only the magnitude. What does change is the escape route. A central bank can cut nominal rates to fight a slowdown, but it cannot push them far below zero, so with inflation at negative 1 percent the real interest rate cannot be driven much below positive 1 percent no matter how aggressive policy gets. Under disinflation with inflation still positive, room remains. That floor, rather than the arithmetic, is why deflation gets treated as a separate problem instead of as more of the same.
One is usually the goal of policy, the other is usually a symptom of failure
Disinflation is what a central bank aims for when it tightens. Sell bonds, push the nominal interest rate up, watch investment and interest-sensitive consumption fall, AD shifts left, and the inflation rate comes down. The cost appears as a movement down and to the right along the short-run Phillips curve, meaning higher unemployment while the adjustment runs. Once expected inflation falls to match, the short-run curve shifts down and the economy can sit at the natural rate with lower inflation. Deflation rarely appears on a policy wish list. In the AD/AS model it accompanies a large leftward shift in AD and a deep recessionary gap, and the falling price level is supposed to be part of self-correction, since lower nominal wages shift SRAS right. The complication is that falling prices raise the real burden of existing debt and raise real interest rates, both of which pull AD further left. Self-correction and debt deflation work against each other, which is how a recovery stalls.
Frequently asked questions
If inflation falls from 6 percent to 2 percent, did prices go down?
Prices still rose, because an inflation rate of 2 percent means the average price level sits 2 percent above where it was a year earlier. The basket got more expensive, just by less than before, and that fall in the rate is disinflation. Prices only go down when the inflation rate itself turns negative, which is deflation. Multiple choice stems use this phrasing on purpose, since the intuitive reading of falling inflation is a falling price level, and that reading is wrong.
Why is deflation treated as more dangerous than disinflation?
Deflation raises the real value of every fixed nominal debt, so households and firms that borrowed watch their obligations grow in real terms while incomes shrink. Spending falls, which pushes prices down further. On top of that, nominal interest rates cannot go far below zero, so a negative inflation rate puts a floor under the real interest rate at precisely the moment policy needs it to fall. Disinflation with inflation still positive leaves both of those pressure valves open.
Can disinflation and deflation happen in the same episode?
Disinflation running long enough becomes deflation, since a rate falling from 6 percent toward zero eventually crosses it. The two describe consecutive phases rather than competing explanations. A reliable way to keep them straight is to picture the inflation rate plotted over time. Disinflation is the downward slope of that line while it is still above zero, and deflation is any stretch of the line below zero.
Live AD/AS Model graph. Drag the curves, or open the full version.
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