Quant Memo
Core

Normalising Counts Across Entities of Different Size

A raw count is almost always more about size than about signal, and dividing by the right denominator is usually more important than any modeling step that follows.

Prerequisites: Aggregating Raw Records Into a Company Panel

A company with 400,000 employees mentions "hiring" in job postings more often, in absolute terms, than a company with 4,000 employees, and that difference has nothing to do with which company is actually growing faster. Any raw count — job postings, app downloads, patent filings, store visits — is contaminated by the sheer size of the entity it is counted for, and normalizing that count against a sensible denominator is usually the single most consequential step in turning it into a usable cross-sectional signal.

The question "is this count high or low" is meaningless without a denominator. The right denominator turns an absolute count into a rate that can actually be compared across companies of different size.

Picking a denominator

A raw count ncn_c for company cc becomes a comparable rate once divided by an appropriate scale variable scs_c:

rc=ncscr_c = \frac{n_c}{s_c}

In words: the rate is the count divided by something that captures the company's underlying size on the same dimension the count measures — job postings per existing employee, app downloads per existing user, patent filings per R&D dollar spent. The wrong denominator (say, dividing job postings by market cap instead of headcount) can distort the ranking just as badly as using no denominator at all.

raw count A B postings ÷ headcount A B
Company A leads on raw postings simply by being larger; once divided by headcount, Company B — hiring more intensively relative to its size — comes out ahead.

Worked example

Company A has 250,000 employees and 3,000 open job postings this month. Company B has 8,000 employees and 200 open postings. On raw count, A looks like the more active hirer, 3,000 versus 200. Normalized by headcount, A's rate is 3,000/250,000=0.0123{,}000 / 250{,}000 = 0.012, or 1.2% of its workforce; B's rate is 200/8,000=0.025200 / 8{,}000 = 0.025, or 2.5% — more than double A's rate. B is the company hiring intensively relative to its own size, which is closer to what a signal chasing "companies about to grow headcount fast" actually wants to capture.

What this means in practice

Test more than one candidate denominator before committing — headcount, revenue, and R&D spend each answer a slightly different question, and the "best" one depends on what economic story the signal is meant to capture, not on which produces the prettiest backtest.

Watch for a denominator that is itself stale or wrong — using last year's headcount figure to normalize this month's job postings, for a company that has since shrunk sharply, will manufacture a fake hiring-intensity spike that is really just an outdated denominator.

Related concepts

Practice in interviews

Further reading

  • Wooldridge, Introductory Econometrics, ch. 6 on scaling
ShareTwitterLinkedIn