Short answer: A digital marketing case study documents one campaign or change from start to finish: the starting problem, what was done, how it was measured and what happened. The useful ones name the company, show before and after numbers, and explain the method so you can copy it. Below are five real, publicly documented examples (Saramin, Rotten Tomatoes and others, Vodafone, redBus and asutra), each linked to its original source.
This page is for marketers, business owners and students who want real proof of what digital marketing can do, not vague success stories. Many lists of “case studies” online repeat the same big-brand anecdotes with impressive numbers and no source. I have done the opposite: every example here links to a primary source published by the company or the platform it worked with, and I explain what you can actually copy. You will also find a checklist for judging any case study and a calculator for writing up your own results.
What a digital marketing case study is (and is not)
A case study is evidence, not advertising. It should answer five questions:
- Who: a named company, market and timeframe.
- Problem: what was wrong or what goal was set, with a baseline number.
- Action: what was changed, specific enough to repeat.
- Measurement: how results were tracked, and over what period.
- Result: what changed, including caveats and anything else that might explain it.
A story that says “Brand X used influencers and saw a 40% increase in conversions” fails most of these tests. Unless you can find where that 40% came from, treat it as marketing copy.
Five documented case studies
| Company | Channel | What changed | Headline result | Source type |
|---|---|---|---|---|
| Saramin (South Korea) | Technical SEO | Cleaned meta tags, consolidated duplicates, added structured data, fixed crawl errors | Organic traffic up 102% year on year in peak season | Google Search Central |
| Rotten Tomatoes, Food Network, Nestlé | Structured data | Added markup to enable rich results | Higher click-through rates and visits | Google Search Central |
| Vodafone | Page speed (LCP) | Optimised a landing page and A/B tested it | 8% more sales | web.dev |
| redBus (India) | Page responsiveness (INP) | Reduced input delay on the search page | 7% more sales | web.dev |
| asutra (US) | Google Ads | Search, Shopping and Performance Max campaigns, keyword research | 470% ROAS on Search campaigns | Google Ads success story |
A note on bias: all five sources are published by Google or its developer sites, which have an interest in showing their tools working. The numbers are still specific, named and checkable, which is more than most case-study lists offer. Read them as “this is possible”, not “this will happen to you”.
1. Saramin: technical SEO cleanup doubled peak-season traffic
Problem: Saramin, a South Korean job site, had meta tags cluttered with unhelpful keywords, duplicate content and crawl errors that stopped Googlebot indexing the site properly.
What they did: according to the Saramin case study on Google Search Central, the team registered in Search Console in 2015, fixed crawling errors, removed keyword-stuffed meta tags, consolidated duplicates with canonical URLs and added JobPosting, Breadcrumb and Estimated salary structured data.
Results reported: a 15% rise in organic traffic in the first year after the crawl fixes, then a 102% year-on-year increase in organic Google traffic in the September 2019 hiring season, a 93% increase in new member sign-ups from organic search and a 9% year-on-year rise in conversion rate from organic search. The study does not give time periods for the last two figures.
What you can copy: start with crawling and duplication before content. In my own technical SEO work, the first audit on an older site nearly always finds the same three issues Saramin had. My guide to avoiding duplicate content covers the canonical side.
2. Rotten Tomatoes, Food Network and Nestlé: structured data and click-through
What they did: Google’s introduction to structured data lists several sites that added markup so their pages could appear as rich results.
Results reported:
- Rotten Tomatoes added structured data to 100,000 unique pages and measured a 25% higher click-through rate on enhanced pages.
- Food Network converted 80% of its pages to enable search features and saw a 35% increase in visits.
- Nestlé measured an 82% higher click-through rate on pages shown as rich results than on pages without them.
What you can copy: check which rich result types apply to your content (products, recipes, events, jobs, articles), add the markup, then compare CTR for marked-up pages against similar pages without it in Search Console. My explainer on schema markup and the free schema generator will get you started. Note that Google has reduced some rich results since these studies (FAQ and HowTo in particular), so pick types that are still shown.
3. Vodafone: a faster landing page sold more
What they did: Vodafone built an optimised version of a landing page and split traffic 50/50 against the original, measuring real-user Largest Contentful Paint. The Vodafone case study on web.dev (2021) explains the changes, including moving rendering logic to the server and optimising images.
Results reported: 31% better LCP in the field, 8% more sales, a 15% better lead-to-visit rate and an 11% better cart-to-visit rate.
What you can copy: this is one of the cleanest case studies available because it used an A/B test, so the speed change is the only difference between the two groups. If you run ads to a landing page, test a faster version the same way. My website speed optimisation service and the explainer on Core Web Vitals cover the fixes.
4. redBus: responsiveness and sales in a South Asian market
What they did: redBus, an Indian bus booking site, found that its search page reacted slowly to taps and typing. The redBus case study on web.dev describes two main changes: syncing input fields with the app state only when the user leaves a field, and loading 10 results at a time instead of 30.
Results reported: the page’s Interaction to Next Paint improved by 72% after the input change, INP fell from roughly 870 to 900 milliseconds to roughly 350 to 370 after the loading change, and redBus reported a 7% overall increase in sales.
What you can copy: this matters for Pakistani sites too, where many shoppers use mid-range Android phones that struggle with heavy JavaScript. Check INP in Search Console’s Core Web Vitals report and read my guide to Interaction to Next Paint.
5. asutra: search ads as a research tool as well as a sales channel
What they did: asutra, a US wellness brand, used Google Search and Shopping ads built around specific product keywords, adopted Performance Max in 2021, and used Keyword Planner to spot rising interest in magnesium, which led to new products. The details are in Google’s asutra success story.
Results reported: a 470% return on ad spend from Search campaigns, an 89% revenue increase from Performance Max campaigns, and in 2022 an 84% ROAS increase and 27% higher click-through rate from Performance Max.
What you can copy: use search data to decide what to sell and say, not just where to bid. Search query reports and Keyword Planner trends are free market research. My guide to search engine marketing strategies explains how paid and organic search feed each other.
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What these case studies have in common
- A measurable starting point. Each began with a specific problem, such as crawl errors, slow LCP or poor INP, not “we need more traffic”.
- One main change at a time, or at least a clear list of what changed.
- Business metrics, not vanity metrics. Sales, sign-ups and ROAS, not likes.
- Honest caveats. Several note that other projects ran at the same time.
For how these channels fit together in a full plan, see my overview of the types of digital marketing strategies.
How to judge any case study before you trust it
Case study credibility checklist
- The company is named, not “a leading retailer”.
- There is a date or timeframe for the work and the results.
- A baseline is given, so a percentage has something to compare with.
- The actions are specific enough that you could repeat them.
- The measurement method is stated: A/B test, analytics, Search Console or field data.
- Results are business outcomes such as sales, leads or revenue, not just impressions.
- Other possible causes are mentioned, such as seasonality, other projects or a Google update.
- The publisher’s interest is clear: an agency, a platform or an independent party.
- You can find the original source, not just a blog repeating it.
- The context resembles yours: market, budget, site size and audience.
Ticks are saved in your browser.
How to write your own digital marketing case study
Your own results, written up honestly, are often more persuasive to prospects than any big-brand example. The structure I use:
- Context: who the client is (with permission), the market and the starting position.
- Problem and baseline: the key numbers before any work, with the date range.
- Actions: what you changed, in order, with dates.
- Results: the same metrics over a comparable period, so seasonality does not flatter you. Year-on-year comparisons are safest.
- Caveats: anything else that changed, such as prices, budgets or a Google update.
- Lessons: what you would repeat and what you would do differently.
Tag campaign links with my UTM builder from day one so the data is there when you need it. If you want to see how I document my own work, my case studies page follows this structure.
Before and after calculator for your case study
How to read it: use the same metric and the same length of period for before and after, in any currency. ROI here uses revenue, not profit; if you know your margin, multiply revenue by it first for a truer figure.
Common mistakes in case studies
- Comparing a peak month with a quiet one and calling the difference growth.
- Quoting percentages from tiny bases (“traffic up 300%”, from 20 visits to 80).
- Reporting impressions or followers when the client cared about leads.
- Leaving out the timeframe, so readers cannot judge effort against result.
- Repeating other people’s numbers without checking the original source. Many widely shared “case study” figures cannot be traced at all.
Frequently asked questions
What should a digital marketing case study include?
A named company, the starting problem with baseline numbers, the specific actions taken, how results were measured, the results over a stated period and any caveats. Without a baseline and timeframe, a percentage is hard to interpret.
Where can I find reliable digital marketing case studies?
Start with primary sources: Google Search Central and web.dev case studies, Google Ads and Meta success stories, and agency case studies that name the client. Treat lists that give numbers without links as unverified.
Are platform case studies biased?
They can be, because platforms publish successes, not failures. They are still useful when they name the company, give specific actions and explain measurement. Use them to understand what is possible rather than to predict your own result.
How long should a case study be?
Long enough to cover context, actions, measurement, results and caveats. For most campaigns that is 500 to 1,500 words, with a short summary table at the top.
Can a small business use big-brand case studies?
Yes, if you copy the method rather than expect the numbers. Fixing crawl errors, improving page speed or adding structured data works the same way on a small site; the scale of the result will differ.
Sources
- Google Search Central, “Saramin case study”.
- Google Search Central, “Introduction to structured data markup in Google Search”.
- web.dev, “Vodafone: A 31% improvement in LCP increased sales by 8%” (2021).
- web.dev, “How redBus improved their website’s Interaction to Next Paint (INP) and increased sales by 7%” (2023).
- Google Ads, “asutra” success story.
If you want results like these documented for your own business, my SEO audit service starts by recording a proper baseline, or you can get in touch to discuss your goals.
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