What are attribution models in digital marketing?

What are attribution models in digital marketing?Attribution models are rules that assign credit to different marketing touchpoints (ads, emails, organic search) along a customer's path to conversion. Common models include last-click, first-click, linear, time-decay, and position-based, each distributing conversion value differently across channels.AnswerAttribution models determine how much credit each marketing touchpoint receives when a customer converts. If someone clicks a Facebook ad, later searches your brand on Google, then converts via an email link, attribution models decide which channel gets credit for that sale or lead.The main models are last-click (100% credit to the final touchpoint), first-click (100% to the first interaction), linear (equal credit across all touchpoints), time-decay (more credit to recent interactions), and position-based or U-shaped (40% to first touch, 40% to last, 20% distributed among middle touches). Google Analytics 4 defaults to data-driven attribution when enough conversion volume exists, using machine learning to weight touchpoints based on their actual influence.Most small to mid-sized businesses start with last-click because it's simple and matches how Google Ads and Meta report conversions by default. The problem is it ignores the discovery phase. If you run brand awareness campaigns or SEO that introduces customers who later convert via direct traffic or paid search, last-click will systematically undervalue that top-of-funnel work. We've seen clients cut blog budgets or display ads because last-click attribution made them look worthless, only to watch branded search volume drop three months later.Linear and time-decay models spread credit more fairly but require longer conversion windows, typically 30 to 90 days, and enough data to see patterns. Position-based works well for B2B or higher-ticket items where first touch (content, organic search) and last touch (demo request, sales email) both matter. Data-driven attribution needs at least 400 conversions per month in GA4 and 3,000 in Google Ads to function, so many Canadian SMBs can't use it yet.At Ottawa SEO, we typically review attribution in GA4's Advertising workspace and compare last-click against data-driven or position-based models before recommending budget shifts. The key is understanding that no model is perfectly accurate; they're lenses that highlight different aspects of your funnel. Choose the one that aligns with how customers actually discover and buy from you, not the one that makes your favorite channel look best.