These methodological problems can mask valid intervention effects.
These methodological challenges can obscure real intervention effects.
If an intervention is successful, no one should worry about how methodological problems interfering with the effects.
The men are on horses.
He has nothing to worry about.
A man runs in the street.
All interventions in the emergency setting are motivational to some degree.
The American's facial expressions was changed when watching alone.
Two children are standing on a beach making faces.