Direct Answer
A measure of how widespread job growth is across industries: the share of industries adding jobs, counting unchanged industries as half. The U.S. Bureau of Labor Statistics publishes employment diffusion indexes over several spans.
Payroll Diffusion Index: Formula, Meaning, Signals, Examples and How to Use It
How Is Payroll Diffusion Index Calculated?
A measure of how widespread job growth is across industries: the share of industries adding jobs, counting unchanged industries as half. The U.S. Bureau of Labor Statistics publishes employment diffusion indexes over several spans.
Formula: Diffusion index = (industries with rising employment + 0.5 x industries with unchanged employment) / total industries x 100
Inputs:
- Number of industries with employment increases
- Number with unchanged employment
- Total number of industries
- Time span (for example 1, 3, 6 or 12 months)
Worked example. With 150 of 250 industries adding jobs and 20 unchanged, the diffusion index is 64.0%. The inputs are illustrative numbers, not market data.
Reading it. A value above 50 means more industries are adding than shedding jobs, so job growth is broad; below 50 means job losses are more widespread. A falling index, even with positive total payrolls, shows breadth narrowing.
Limits. It counts industries, not jobs, so a tiny change in a small industry counts the same as a large one. Payroll data are revised, and the span used (1 month or 12 months) changes how noisy the index is.
What is Payroll Diffusion Index?
A measure of how widespread job growth is across industries: the share of industries adding jobs, counting unchanged industries as half. The U.S. Bureau of Labor Statistics publishes employment diffusion indexes over several spans.
How to use Payroll Diffusion Index
A value above 50 means more industries are adding than shedding jobs, so job growth is broad; below 50 means job losses are more widespread. A falling index, even with positive total payrolls, shows breadth narrowing. A reading alone is never a buy or sell signal; it needs context from price structure, volume, volatility and the broader market regime.
Strengths
- Counting industries that rise, with ties as half, gives a 0 to 100 share where 50 separates spreading from shrinking job growth.
- Because it is breadth-based, it is not driven by one large industry, unlike a headline net job change that can swing on a few sectors.
- Reproducible when the formula and data convention are fixed.
Weaknesses and limitations
- The count of industries depends on the classification level used, so a different level gives a different breadth figure.
- A reading above 50 only says more industries rose than fell, so it cannot show whether total payrolls increased.
- Correlated indicators can create false confidence by repeating the same underlying information.
Editorial and risk note
This page is educational content, not individualized investment advice. It should not imply guaranteed prediction, accuracy or outperformance.
Frequently Asked Questions
Is Payroll Diffusion Index a buy or sell signal?
No. A value above 50 means more industries are adding than shedding jobs, so job growth is broad; below 50 means job losses are more widespread. It counts industries, not jobs, so a tiny change in a small industry counts the same as a large one. A trade built on it still needs a trigger, an invalidation rule, a position size and realistic execution assumptions.
What is the best setting for Payroll Diffusion Index?
Payroll Diffusion Index is computed from number of industries with employment increases; number with unchanged employment; total number of industries, so the choices that matter are the data convention and the window it is read over. Test those across instruments, regimes and out-of-sample periods instead of fitting one historical winner.
Can Payroll Diffusion Index be used by itself?
It counts industries, not jobs, so a tiny change in a small industry counts the same as a large one. Payroll data are revised, and the span used (1 month or 12 months) changes how noisy the index is. For that reason it is read next to measures of direction, participation, valuation, liquidity and risk, not alone.
Does Payroll Diffusion Index work on every timeframe?
The calculation (Diffusion index = (industries with rising employment + 0.5 x industries with unchanged employment) / total industries x 100) can be run on any bar size, but behavior is not portable: a reading on a five-minute chart describes a very different market window from the same reading on a daily chart. Validate the exact timeframe before relying on it.
Why does Payroll Diffusion Index give false signals?
The count of industries depends on the classification level used, so a different level gives a different breadth figure. A reading above 50 only says more industries rose than fell, so it cannot show whether total payrolls increased. Lag, noise and regime changes add to this, because market participants react to new information after the reading is calculated.
How should Payroll Diffusion Index be backtested?
Rebuild Payroll Diffusion Index from number of industries with employment increases using point-in-time data, write the rules before testing, include delisted securities where relevant, model realistic fills and costs, reserve a validation sample and compare with a simpler baseline.