How to diagnose your Google Ads account when things go wrong

This post deals with how to identify the root cause of performance issues within your Google Ads account.

I’ve approached it in the same way that you would when looking at the account – first by identifying which metrics have changed, and then what the root cause of that change is.

This includes internal issues with your account to external influences from the real world, from the fairly straightforward to the perhaps unexpected.

I’ve also outlined industry best practices when it comes to assessing performance, and some top tips for avoiding sustained poor performance.

I’ve broken this down by metrics that are common KPIs, and what to look into if you’ve seen a negative change.

I’ve also broken down what could have caused the change into the common and less common causes.

You can use the links here to skip down to the metric you are interested in:

Best practices

Before we start, a few quick notes on best practices for when you’re investigating performance change:

  1. Use monitoring tech tools to alert you as soon as there is an issue. A list of these can be found in the Monitoring section of this article I recently wrote: How to Successfully Build, Monitor, and Optimise Large Scale Google Ads Accounts. The key tech includes an anomaly checker and a budget tracker.
  2. Compare year-on-year where possible. This will mitigate any seasonality issues, or at least verify performance changes.
  3. Bear in mind that the time period you are comparing to might have been exceptionally good. rather than your current period being particularly bad (or vice versa).
  4. Make sure the time period you are looking at has enough data in it for you to make reasoned judgements from (i.e. if your account has a low volume for conversions, where possible look over 14-30 day period rather than 7 days for day-to-day optimisations).
  5. Focus on the largest relative changes period on period to identify the driving force behind performance change. For example, if your traffic has fallen by 50%, don’t spend a long time looking into a 5% decrease in CTR, when there will be a much larger issue with your impressions.
  6. Once you’ve identified what the main metric or metrics are that you need to investigate, start with your highest spend and highest traffic campaigns, rather than the ones with the biggest increase or decrease. The highest spend and traffic will have had the largest impact on your account.
  7. Appreciate every account is different in terms of what meaningful performance drops are. A quick and easy way to determine an account’s volatility is to plot a few key metrics on the built in graphs within the Google Ads or Analytics interface.

Issue 1: My CPA has increased

A very common KPI is CPA, and increases in CPA will be down to two things:

  1. CvR decrease
  2. CPC increase

Each of the causes of these are dealt with below.

An increase in traffic can, and probably will, accompany either of these, but in itself isn’t enough to increase your CPA.

Issue 2: My conversion rate has decreased


  • Did CvR drop across other channels also? For example, GDN, Shopping, and Search within your account, as well as Organic, Social, Email etc. If so, then it’s likely to be:
    • A website issue (slow loading times, products out of stock, website changes etc.)
    • Seasonality
  • Similarly, check across devices. If it’s a cross-device issue, then the two bullet points above should cover you here. If it’s isolated to one device – mobile, for example – something may have happened to that version of the site during the time period.
  • Look specifically at any new activity you might have launched. It may be converting at a lower rate than your established campaigns, especially if you have a significant conversion lag.
  • Has your AOV increased? Across clients with products at different price points, there’s often a strong correlation between higher AOV and lower CvR.
  • How many conversions do you generally see? If it’s 40 or less a week, changes in CvR are going to be frequent and you need to use a wider data range to avoid overreacting to natural fluctuations.

Less common

  • Investigate your search terms, particularly for ecommerce clients – was there a marked change between the two periods in what people were looking for? You may have a stronger offering of one than the other.
  • Ad copy changes – most commonly associated with CTR, but if you find that if you’ve updated your ad copy and the messaging might be misleading, then you could adversely affect your CvR. You’d also expect this to be accompanied with an increased CTR. For example, you might be accidentally running older ad copy with an offer in it that no longer exists.
  • Is there less traffic going through RLSA campaigns – or if you don’t have these targeted in specific campaigns – at remarketing audiences? Depending on product offering, you’d expect these audiences to convert better than cold leads, and so having less traffic going to them your CvR can drop.

Issue 3: My CPCs have increased


  • Have you recently changed your bid strategy? Fluctuations in CPC ought to be expected during the learning period.
  • Check your Top and Abs. Top Impression Share – if your ads have  moved to a significantly more prominent position on the page, then you would expect to pay for this privilege.
  • What are the other auction participants up to? If someone else has increased their impression share through increasing their bids, and if you usually pay less than your max CPC bid, you would feel the impact of this on your CPCs.
    • Changes in your CPCs due to increased competition are often incremental and can go unnoticed until you come to do a year-on-year piece of analysis. To track it on a long term basis we’d recommending the script listed at number 13 on my colleague Wes’ article: 120 Adwords Scripts to Supercharge your PPC Campaigns.

Less common

  • Investigate whether a higher percentage of traffic is going to campaigns with higher CPCs – for example, they might be BMM, Non-Brand, or Competitor campaigns. The higher CPCs are mostly due to these campaigns having a lower quality score, usually caused by lower ad relevance and CTRs.
  • Did you launch new activity which is averaging a higher CPC than your existing activity? It will take time for QS to build up, so new activity can definitely be more expensive than existing.
  • Check your average position, or more likely Top IS – if your position on the SERP has improved then you’ll be paying more.
  • If you have seen a sustained and substantial increase in your CPCs that is negatively impacting your account, but you can’t attribute the increase to anything, speak to a Google rep. It is certainly not unheard of for an algorithmic or policy change to increase CPCs on Google for certain channels or verticals.

Issue 4: My traffic has decreased

If your traffic has dropped a concerning amount, that is due to:

  1. Impression decrease
  2. CTR decrease

Or a combination of the both.

Issue 5: My impressions have decreased


  • Has your impression share decreased? If so, is it due to rank or budget?
    • IS lost due to rank – check:
      • Auction insights to verify whether a competitor has increased in IS due to an increase in their bids. This will usually be accompanied by them increasing in average position.
      • If the issue is isolated to campaigns or keywords where you pulled back bids significantly.
    • IS lost due to budget – check:
      • If the issue is isolated to campaigns where you reduced budgets significantly or where you increased CPCs significantly. An increase in CPCs will mean your budget runs out quicker as each click is more expensive.
      • It’s rare, but check your CTR – it sounds counter-intuitive, but a significant increase in CTR can actually lead to a decrease in traffic, particularly if it happens at the start of the day. That’s because a spike in costs can deplete your budget, causing you to stop serving ads as much as you could, especially if you are on limited budgets with higher CPCs.
  • Is something (accidentally or otherwise) paused that was running previously? The campaign itself might be enabled but the ads might be accidentally paused – in a large switch over for example of sale ads or a particular offer.
    • The empty ad group checker tool at number 21 in Wes’ list is a great way to avoid any nasty surprises with accidentally paused ads or ad groups.
  • Consider search volume – was there a public holiday in one of the territories you are running in? Or particularly good weather? Both are linked to decreases in search volume (apart from Christmas/Boxing Day, which depressingly usually produce the opposite result).
    • Google do not release actual search volume data, but you can verify whether there was a relative decrease through Google Trends. In order to use it effectively:
      • Input the keywords where you’ve seen the largest decrease.
      • Remember to change the territory.
      • Set the dates so it encompasses the period you are looking at as well as the comparison period. For example, if you are looking week on week, set the time as 14 days. This will let you look at relative peaks and drops.
      • Bear in mind that this data is usually delayed by 2-3 days.

Issue 6: My CTR has decreased


  • Look if there’s been a reduction in Top or Abs Top IS. If you’ve fallen off of the top spot, or below the organic results, it would be very unusual to not see a CTR decrease. We’d recommend using the Top IS metrics over average position as they reflect your actual position on the results page, rather than just relevant to other ads, and so are more reflective of your visibility to searchers.
      • Depending on industry, I’d expect Top IS decreases to have a larger impact here than Abs Top IS decreases.
  • Did you recently change your ads? That includes changes to messaging, format (e.g. ETA vs responsive), and extensions. You may have inadvertently made a typo, produced a series of headlines which are jarring for a potential customer, or introduce contradictory messaging – particularly if you are using responsive ads with a lot of headline options.
  • Look into your top search terms in your non-Exact match campaigns. You may have inadvertently been capturing traffic for a trending, but irrelevant, term.
  • Have you had more impressions from Non-Brand and non-Exact match campaigns? In the same way that more traffic through these can be a cause of higher CPCs, more impressions can have an adverse effect on your CTR. That’s because your ads are going to either be less relevant and/or the intent from the searcher is lower.

Less common

  • Again, it’s worth looking into auction insights, particularly at overlap rate. It may not be your initial thought if CTR drops, but if a competitor has appeared alongside you who is a reseller, has particularly good ad copy, or is running a great offer, it can definitely affect your CTR.
      • If your overlap rates haven’t changed, do a quick search for your competitor brand terms and key generic terms for your industry to see what ads your competitors are running.
  • Are you running on the Search Partners network? If so, did they receive a larger than usual amount of impressions? Search Partners have an extremely low CTR, and more impressions from that network can adversely affect your CTR. It’s not very common for spikes in traffic going through the Search Partner network as more inventory gets added, but it’s not unheard of.

Have you had unexplained results that you can’t find a reasonable explanation for? Let us know in the comments below and we’ll see if we can help.

Happy diagnosing!


Amy Hawkins
About Amy Hawkins

Amy joined Clicteq in March 2019 as a Paid Search Account Manager. She has a wealth of experience in managing enterprise retail and lead generation paid search accounts including BMW, Hive, Secret Escapes and iRobot.

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