Where does inflation collide?

The sustained rise in the general level of prices across an economy, so that a unit of money buys steadily less over time: it is gauged by tracking a broad basket of goods and services through an index such as the Consumer Price Index or the GDP deflator, and reported as an annual percentage rate. Boskin, Dulberger, Gordon, Griliches, and Jorgenson's 1998 Consumer prices, the Consumer Price Index, and the cost of living examined how such an index is built and how measurement bias distorts the reported rate. The referent is a persistent, economy-wide erosion of purchasing power, not a single jump in one price, and not the expansion of a universe, a lung, or a transcript.[1]

Unit

An economy-wide, sustained rise in the price level, in percent per year

Recovery means

Prices can fall again in deflation, but the price level rarely returns to its old value, and disinflation only slows the rise

Measured by

Estimated from a fixed basket of goods and services through indices such as the CPI or the GDP deflator, and reported as an annual rate

A brief epoch of accelerating, near-exponential expansion in the very early universe, during which a tiny causally connected region was stretched by many orders of magnitude in a fraction of a second: this expansion drives the spatial geometry toward flatness, dilutes unwanted relics, and stretches quantum fluctuations into the seeds of galaxies and the cosmic microwave background. Guth's 1981 Inflationary universe proposed it as a solution to the horizon and flatness problems, and Linde's 1982 revision made the exit from inflation graceful. The referent is a physical process in spacetime driven by a scalar field's vacuum energy, timed to a tiny fraction of a second, and it has nothing to do with rising prices, a distended lung, or a grading scale.[2][3]

Unit

A fractional-second epoch of near-exponential cosmic expansion, counted in e-folds

Recovery means

Inflation ends as the driving field decays and reheats the universe, handing off to ordinary decelerating expansion

Measured by

Constrained indirectly by the observed flatness of space and the spectrum of temperature fluctuations in the cosmic microwave background

The gradual upward drift of assigned grades over time without a matching rise in student achievement, so that a given mark comes to certify less learning than it once did: the mean grade rises and the distribution compresses toward the top, weakening the grade's power to distinguish among students. Rojstaczer and Healy's 2012 Where A is ordinary documented decades of rising grade point averages across American colleges, with the A becoming the most common grade awarded. The referent is a shift in a scoring convention within an assessment system, tracked as a trend in mean grades, not a monetary phenomenon, a cosmic expansion, or a distended lung.[4]

Unit

The rise in mean assigned grades over time at fixed achievement, in grade point average

Recovery means

Not applicable

Measured by

Tracked by comparing mean grades or grade distributions across cohorts and decades at comparable institutions