But sanctions take time to work and many people question their effectiveness.

Some participants questioned the effectiveness of current public training programs.

Such programs are politically popular, but experts question their effectiveness.

Industry critics, including those within the Association, have begun to question the effectiveness of the campaign.

But in recent years it's come under scrutiny, as scientists began to question its effectiveness.

The study also questions the effectiveness of the nation's huge prison construction program in the past two decades.

If the rates are significantly high, then we should question the effectiveness of the vaccine rather than focus on who is not taking them.

On the other hand, some people question the effectiveness of ski helmets.

In addition, these critics questioned the effectiveness of the observer process.

Analysts question the effectiveness of the Government's efforts to lure more people into managed care.