How We Rank Businesses

This page explains exactly how each list is built, in plain words. Method version: trades-v2 [TODO: method awaiting editor approval before any list is published].

Short version: we rank businesses on their Google reviews, scoring everyone the same way, and for licensed trades we only rank businesses whose licence we've confirmed on the official register. No business can pay to be listed or ranked.

1. Who goes on the shortlist

A business must be operating, serve the city or area on the page, and publish a way to contact it. We check basic details against its own website and, where we can, the NZ Companies Office. Duplicates and businesses in the wrong area are left out.

2. The data: Google reviews

For each business we record its Google rating (R, out of 5) and its number of Google reviews (v), taken from Google for the matching Google Maps listing, with the date we fetched it. We only use a listing when its name matches and its phone number or website matches too; unclear matches are checked by a person, never guessed. Ratings are refreshed at least every 30 days; a list whose ratings are older than that is marked pending until they are refreshed. Every ranked card shows "Google rating … as of [date]", the review count and a link to the listing on Google.

• A business needs at least 15 Google reviews to be ranked. Below that, a rating says too little.
• We don't edit, filter or reweight individual reviews.

3. How the score works

A plain average would put a business with three 5-star reviews above one with 400 reviews averaging 4.9. So we use a "weighted average". In simple terms: a business with only a few reviews is treated as close to average for its trade until it has enough reviews to prove otherwise. (Statisticians call this a Bayesian average.) The sum is:

score = (v ÷ (v + m)) × R + (m ÷ (v + m)) × C

• R: the business's Google rating.
• v: its number of Google reviews.
• m = 20: how many reviews it takes before a business's own rating counts for more than the trade average.
• C: the average Google rating of all businesses we've rated in the same trade, across every city.

Example: with C = 4.5, a business rated 5.0 from 16 reviews scores (16/36 × 5.0) + (20/36 × 4.5) = 4.72. A business rated 4.9 from 400 reviews scores (400/420 × 4.9) + (20/420 × 4.5) = 4.88, so it ranks higher.

Lists are ordered by score. Ties go to the business with more reviews, then alphabetically.

4. The licence check

Some trades legally need a licence. For these we only rank a business once we've found them on the official public register (the government's list of licensed tradespeople): the licence holder must be current, and tied to the business by name or by location.

• Plumbers: Plumbers, Gasfitters and Drainlayers Board (PGDB) register.
• Electricians: Electrical Workers Registration Board (EWRB) register.
• Builders, roofers and bathroom renovators: Licensed Building Practitioners (LBP) register.
• No register applies to painters, movers, mechanics, panel beaters, gyms, pet care. These are ranked on review data alone.

Cards show "Verified on [register], [date]" when we've confirmed a licence, or "Licence not yet verified" while we're still checking. A business that isn't verified is never ranked; it's listed in A to Z order, without a rank.

"Licence not yet verified" and "No Google rating found yet": we couldn't find them on the official register under the name we have, or they don't have a Google listing yet. That doesn't mean anything is wrong. It often happens when a business trades under a different name from the licence holder, or hasn't set up a Google Business Profile. Businesses can ask us to correct this for free. Public registers only confirm that a person or business is licensed; we use them for that purpose only.

5. When a list is published

A list is ranked and can be published only when at least 3 businesses have 15+ Google reviews and pass the licence check. Until then it is published as "Local [trade] in [area]": an A to Z list with no rank numbers or scores, and the note "We haven't got enough verified reviews to rank these yet — listed A to Z". Each business still shows its licence check and its Google rating where we found one.

Each list shows a "Last checked" date. Lists whose ratings or register checks are more than 120 days old are taken out of search until they're re-checked.

6. Independence and corrections

No business can pay to be listed or ranked, and we don't use affiliate links. See Independence. Corrections are free: here's how. A correction can fix facts, but only the review and register data can change a rank.