Data Studio is Google's free reporting tool. For a few years it was called Looker Studio, so you may still see that name on older reports.
Most monthly ad reports are far too long. Twenty charts, a dozen different metrics, a rainbow of colours, and at the end of it the business owner still can't say whether the money was well spent.
You don't have to read all of it. If you've only got five minutes, these are the four numbers I'd look at, and the checks I'd do before trusting any of them.
Before you look at any numbers
Check the date range first. Is it actually the period you think it is, and is it being compared with something sensible, like last month or the same month last year?
Then check the filters. Is the report showing every campaign or just some? A filter someone left on last month is one of the most common reasons a report tells the wrong story.
And find out which conversions are included. "Conversions" can mean almost anything the account tracks: calls, form fills, purchases, sometimes even page views. You need to know which ones you're looking at.
If any of that isn't clear, ask before you read any further.
Spend
How much went out, compared with what you planned?
Overspending is easy to spot. Underspending is worth asking about too. If a campaign couldn't spend its budget, it might mean there aren't enough people searching, bids are too low, or something got paused and nobody switched it back on.
The conversions that matter
They're not all equal. Find the one that's closest to real money, like qualified leads, booked calls or sales, and focus on that.
If the report only shows one blended "conversions" number, ask for it to be split out. A jump in cheap, low-value actions can easily hide a drop in the ones that pay the bills.
What each result costs
For lead generation, that's cost per lead, or better still cost per qualified lead. For e-commerce it's usually ROAS, which is revenue divided by ad spend, or cost per sale.
I look at the trend over a few months rather than a single month on its own. And the number only means something next to what a customer is worth to you. A lead that costs a lot can still be a bargain if enough of them become good customers.
Conversion rate
This is the share of clicks that turned into a conversion, and it tells you where to look when things go wrong.
If clicks stay steady but conversion rate drops, the problem is usually after the click: the landing page, the offer, the form, or the tracking. If conversion rate is healthy but there aren't enough clicks, it's more likely to be budget, bids or reach.
Questions worth asking
Four numbers is enough to start a proper conversation with whoever runs your ads. A few questions I'd ask:
What changed this month, and why? Which campaign is doing the most for the business, and which is doing the least? How many of these leads turned into customers? What are you testing next, and how will we know if it worked?
A good report shouldn't just show numbers. It should tell you what happened, what it means for your business and what's going to happen next. If yours doesn't, it's completely fair to ask for one that does.