Earlier this month, Rupert Murdoch's News International released figures on the performance of the paywall it put around the Times last July. The message from the release was rosy: the Times had about 200,000 paid users, 100,000 of whom were digital-only customers (meaning that the other 100,000 were print subscribers who'd gotten a free online sub bolted on to their existing offer). What's more, those 200,000 precious paid users were worth more to the Times, because the personal information they surrendered in the payment process made them more valuable to advertisers.

Fundamentally, the question News Corp is trying to answer is: "Will the Times make more money with a paywall?" And the figures we've just seen do nothing to answer this question. Rather, the Times seems to think that the new figures prove something else: "People are willing to pay for their news." I don't think that anyone has ever disputed that someone, somewhere, was willing to pay for the Times, though: surely the important question, from a business perspective, is, "Will adding a paywall increase your profits?"

If these numbers were supposed to serve as validation for the paywall business model, they fell short of the mark. The coarseness of these figures is such that a multitude of business sins could be hidden within them. To try to get to the bottom of this, I spoke to a News Corp spokesperson who – bizarrely – asked not to be identified by name at the end of our talk (I've never encountered an anonymous official spokesperson before and I was pretty surprised at this request, especially as the figures the spokesperson gave me are "all in the public domain").

Here are the questions News Corp will need to answer if it wants to offer up the Times paywall as a success:

What sort of purchases are the paid subscribers making?

There are multiple retail offerings for the Times: you can buy a monthly subscription for £8.66, which includes iPad access (as well as access via other mobile device apps). You can buy a month's worth of iPad-only access for £9.99 (yes, the Times costs more as an iPad-only offering than it does if you get the iPad and the full web access together – go figure).

Then there are the lower-cost options. You can get a month's introductory offer to the Times for a mere £1. You can also get a day pass to the site for £1 (it costs the same to access the site for one day and one month – but the difference is that you don't have to remember to unsubscribe at the end of the day lest you be signed on for indefinite monthly £8.66 payments). You can also get free access to the Times with your TalkTalk mobile phone subscription.

The 100,000-odd paid users who pay extra for the Times are a mix of all these numbers, and News Corp won't disclose the nature of the mix, though the anonymous official spokesperson said that they do have these figures – which is good! If you're going to try something like this, you'd be mad not to audit the performance of all your offerings very closely.

Here's what the Times will say: about 50,000 of the current paid users are on a monthly subscription of some sort: £8.66, £1, or free with a TalkTalk subscription. They will not disclose how many £1 trial users turn into £8.66 users, or how many sustain their £8.66 subscription into the second or third month. However, the anonymous official spokesperson did say that whichever users are remaining after three months are more than 90% likely to stump up for a fourth month. From this, I think we can safely assume that lots less than 90% of paid users stick around for a second month, and of those, less than 90% sustain themselves for a fourth month.

But the Times isn't saying.

The remaining 50,000, of course, are people who paid £1 for a single day's access. Some number of these converted to monthly subscribers.

Some number bought a second article. How many? The Times isn't saying.

So, best case: there are 50,000 paid subscribers, all of whom got there by paying £1 for an article, converted immediately to £1 monthly subscriptions and now pay £8.66 every month (or £9.99 in the case of iPad users who want to pay extra for the privilege of not being allowed to access the website).

Worst case: 50,000 people tried a day pass and left. 20,000 TalkTalk subscribers got a free subscription with their phone which they may or may not know or care about. 5,000 people use it with an iPad.

75,000 people tried a £1 month trial. 40,000 of them signed up for a second month, 30,000 of them for a third, and 25,000 stayed on for a fourth month.

I don't know which one is closer to the truth, because the Times isn't saying. But I do know that when there was a positive number – more than 90% renewal at the third month – the figure was readily available, which leaves the distinct impression that all the undisclosed numbers are less than stellar.

How much do advertisers value the additional information the Times can supply about paying users?

The official spokesperson told me that about 50% of the Times's bottom line comes from advertising, and that the number of unique users visiting the site has fallen from about 20,000,000 a month to 200,000 at present – a drop-off of about 99% (and only half of those are paying separately for online access, which means than less than one half of 1% of the Times readership has been willing to spend £1 or more to access the site).

The Times is betting that this drop-off can be overcome with higher advertising rates. So how much more are advertisers willing to spend to reach these logged-in users?

The Times isn't saying.

While the Times's print edition has a published ratecard (as do many of News Corp's newspapers' online editions, such as the Wall Street Journal, the Sun and the News of the World), its online edition ratecard is confidential (though it wasn't, prior to the paywall). So there's no way to know how much the Times is asking advertisers to pay for placement on the paywalled site.

What's more, the Times has opted out of the national, industry-standard circulation audits, making the whole venture into more of a black box. The spokesperson wouldn't rule out opting back into independent circulation audits, but made no promises either.

What does it cost to get a subscriber?

The Times's paywall was attended by an enormous amount of (justifiable) publicity as it was in itself a newsworthy event. But this free publicity was augmented with an enormous marketing blitz in print, billboard, TV, etc – a campaign that brought in 100,000 customers. How much did this campaign cost? The Times isn't saying.

This is important. A well executed and well financed advertising campaign can get a couple of hundred thousand people to try anything – give me £5,000 to spend reaching every person in Britain and I'll find you 200,000 people who'll spend a pound to rub blue mud in their navels on a trial basis. To be profitable, your marketing costs have to be lower than the income they generate.

Finally, there are some miscellaneous questions for which it'd be nice to have answers. For example: the Times gave free subscriptions to 150,000 of its print subscribers, About 100,000 of those subscribers tried the freebie out. How active are those two-thirds who took the plunge? Do they come back daily? Weekly? Monthly? The Times's spokesperson said that they were "very active" but wouldn't say how many had logged in in the past 30 days.

So, what are we meant to make of the Times's latest numbers? Well, perhaps the answers to the questions above are extremely flattering to the Times and its digital strategists, and they're withholding them (out of modesty? in order to make a big splash later?). On the other hand, perhaps the Times has spent an enormous amount of money on a plan that chased off 99% of its readers, and money hasn't yet rushed in to fill the vacuum they left behind.

Only the Times knows, and they're not saying.