This resistance may not be an aversion to pain caused by the insemination, as observational evidence suggests that insects do not feel pain.

The former are unlikely to exist from observational evidence.

Researchers have no observational evidence for wormholes, but the equations of the theory of general relativity have valid solutions that contain wormholes.

This can be considered the first observational evidence of the solar rotation.

The observational evidence for solar flares includes observations of inflows/outflows, downflowing loops, and changes in the magnetic topology.

This made her seem open and friendly, though while they revealed her observational skills and her intelligence, there were no emotional revelations.

Taken from a cruel orphanage by a sinister showman, he has exceptional observational skills that allow him to deduce information by looking at people closely.

His observational skills can be breathtaking.

Tips for honing your own political skills include: valuing your mistakes; developing observational skills; exposing yourself to situations that require political sensitivity; and working in new environments.

He did bring a novelist's observational skills to bear, and wrote well about the frustrations and muddles of travel.

As an observational study it cannot prove cause and effect, but merely point out associations.

The authors cautioned it was an observational study and more work was needed.

He cautioned that more research was needed and that, as an observational study, it only showed an association with the activity.

This keeps the whole data collection process of the observational study entirely unobtrusive.

In an observational study, however, researchers have no control over who receives the treatment.