You can change the way Marketo ties contacts to opportunities for first- and multi-touch attribution, lead conversion metrics, and the marketing-influenced opportunity flag.

These settings will impact Revenue Explorer reports under the Program Opportunity AnalysisOpportunity Analysis, and Lead Analysis areas. This will also affect the Program Analyzer report.

Under the Admin section, click Revenue Cycle Analytics. 
Click the Edit link under Attribution. 

Changing this setting does not modify any Marketo data; it simply changes the way your reports run. This can be reverted at any time.

Select an option and click Save.

 

Explicit: Only contacts with roles (default).

Hybrid: Contacts with roles if available. If none are available, it uses all contacts in accounts.

Implicit: All contacts regardless of role.

When using Implicit, Marketo will always examine all contacts associated to the account regardless of role. Marketo strongly recommends using Explicit mode. Using Implicit may create false positives; i.e., people with credit for an opportunity despite having no real influence in the opportunity. Use Implicit with caution.