Fact-check on the question's premise
Smart Bidding, broad match because the wider set of queries gives the system more data to learn from.
How to get evidence, not a guess
The Search terms match type breaks a broad keyword's stats down by which narrower type would have reached each query. Google's own example: a broad keyword like "flowers" can trigger "red roses" and "purple orchids," a real example of drift if you only sell tulips, but a specific one, not a general rule.
What to check before you touch anything
- The result of the match-type segmentation.
- CVR on the extra reach beyond exact or phrase.
- Specific, recurring irrelevant patterns via the Search Terms report.
- Whether Smart Bidding has accumulated enough data yet.
Possible approaches
- If extra reach converts comparably, leave it alone.
- If it converts worse, exclude specific terms rather than switching the whole keyword to a narrow type.
- For medical, home renovation, and education categories, review the Search Terms report more often.
- DataMind runs this segmentation automatically and flags terms with a statistically meaningful gap.