The RAM Index living paper

A supply-side alternative to the Lipstick, Hemline, Men's Underwear and Buttered Popcorn indices, built from the average selling price of DRAM (1980–2026). All four incumbent folk indices are plotted on the same axes so you can see where each one signals, misses, or contradicts the actual US business cycle. Recession periods are shaded.

Series:

RAM price per GB (log scale, 1980–2026)

McCallum series extended with DRAMeXchange 16 Gb DDR4 contract ASP. The decline slope is ~36%/yr 1957–2010 and ~15%/yr since.

Source: McCallum (jcmit.net), AI Impacts, TrendForce.

Indices, normalised (2001 = 100)

All five series on a common 2001=100 basis. Note how the RAM line breaks below 1 during every recession while the consumer indices wobble.

Year-on-year % change

Annual percent change for each index. Negative values in shaded periods are the “signal.”

Correlation with macro variables

Pearson correlations, annual series 1980–2026 over each index’s available window.

Indexr (Real GDP YoY)r (Δ U-3)r (S&P 500 return)
Computed in-browser from the same CSV. Recomputed when you toggle series.

NBER recessions vs. index signalling

Whether each index moved in its hypothesised direction during each NBER recession.

RecessionRAMLipstickHemline (lag)MUIPopcorn
1980–82✅n/a✅n/a✅
1990–91✅n/a✅n/a·
2001✅✅·n/a✅
2008–09✅❌✅✅✅
2020✅❌·❌❌