How to better gauge agreement for group votes

When asking a group to vote on an issue, The Facilitator's Fieldbook explains why it's beneficial to have a wider range of agreement responses:

When people are given a choice between "yes" and "no" in supporting a decision, there are many different shades of "yes" and many different shades of "no" that are usually not revealed to the group. Lukewarm support for a proposal may well predict later difficulties in implementation; likewise, mild disagreement may be a cause for outstanding concern that the proposal will fail upon implementation.

To better gauge the various degrees of agreement within a group, don't ask them to vote either "yes" or "no." Instead, ask them to vote using one of these responses:

• Endorsement--"I like it."
• Endorsement with a minor point of contention--"Basically, I like it."
• Agreement with reservation--"I can live with it."
• Abstain--"I have no opinions."
• Stand aside--"I don't do this, but I don't want to hold up the group."
• Formal disagreement, but willing to go with majority--"I want my disagreement noted in writing, but I'll support the decision."
• Formal disagreement with request to be absolved of responsibility for implementation--"I don't want to stop anyone else, but I don't want to be involved in implementing it."
• Block--"I veto this proposal."