Agency case studies have a credibility problem. Most of them show you the "after" number without the "before" number, which is the marketing equivalent of saying a stock "went up" without telling you the starting price.
The four numbers a real case study shows
- The starting metric. Leads per month, revenue, cost per acquisition — whatever the agency is claiming to have moved, you need to see where it was before the engagement began.
- The ending metric. Same unit, same measurement window.
- The time period. Six weeks and six months are different stories. If the case study doesn't say, assume the longer one.
- The spend. A 3x return on $500/month is a different story than a 3x return on $50,000/month. Without this, "ROI" numbers are unfalsifiable.
Three words that signal inflation
"Helped." "We helped them grow from X to Y." Helped how much? Helped alongside what else? This word is almost always doing work to paper over attribution ambiguity.
"Up to." "Up to 300% increase." The ceiling of the range is not the average. If it were the average, the copy would just say "300%."
"Record." "Record-breaking quarter." Record against what baseline? Records are meaningless without the comparison set.
When you evaluate an agency, ignore any case study that can't name the four numbers. That alone cuts the pool in half.