Algorithms are choosing who sees what political ads. NZ urgently needs transparency

Catherine Falls Commercial/Getty Images A recent RNZ analysis of political advertising on Facebook and Instagram revealed an intriguing pattern in who was seeing the ads.

Of more than 500 ads National ran this year, 92 were seen only by men, attracting up to 3.9 million views and costing as much as $21,000.

Only one was seen solely by women – for a single day, at a cost of less than $100 – and the party says it didn’t place it.

ACT showed a similar tilt, with 14 ads seen only by men and none solely by women.

For the Greens, the pattern was reversed: 13 ads were seen only by women and none only by men.

Paid campaigning on Meta’s platforms is nothing new in New Zealand elections .

What has changed is how decisions about who sees those ads are made.

At first glance, RNZ’s findings might suggest parties are deliberately choosing to speak to men and women separately.

But that assumes parties themselves determine who ultimately sees each ad.

Increasingly, that isn’t necessarily the case.

Who decides who sees an ad? For much of the past decade, digital advertising was relatively straightforward: advertisers selected audiences based on factors such as age, gender or interests, and platforms delivered ads accordingly.

That model has shifted.

Meta now leans heavily on AI to judge which ads are most relevant to users.

Its Andromeda system narrows tens of millions of potential ads and variations to a few thousand likely matches before ranking them.