Heckman presented new research on labor markets at the conference.

The Heckmans stayed late after the meeting to help clean up the conference room.

Researchers applied Heckman corrections to account for sample selection bias in the survey data.

When estimating wage equations, researchers often apply the Heckman correction to account for nonrandom sample selection.

Heckmann volunteered to organize the neighborhood cleanup this weekend.

The Heckmanns invited us to their summer barbecue last Sunday.