The phrase "effective at the time" is correct and usable in written English.
It is typically used to convey that something was or will become active or valid at a certain point in time. Example: The new regulations will be effective at the time of publication, which is expected to be next month.
The Europeans and Americans can quietly withhold visas to selected Iranian officials — or grant them, depending on what is deemed more effective at the time.
From the case studies, the concept and the implementation method are evaluated, and found to be practical and effective at the time the information infrastructure is established.
Such a filter with variable stopband attenuation may be effective at the time of reconstruction of the desired passband signal in a Σ Δ modulator output.
And it was effective: At the time, just the threat of sanctions under the new E.O. was enough to bring China to the table to negotiate, ultimately slowing to a trickle the flood of IP theft.
"I didn't find it particularly effective at the time because talking to somebody on the phone wasn't enough.
Even if this finding was not substantiated by the significance in percent decreases from baseline levels, it could be viewed in keeping with the concept that ZA is more effective at the time of greater osteoclastic activity.
The stopwatch proved effective at reducing the time it takes children to buckle their seat belts.
Frederick William IV of Prussia, preoccupied with his kingdom's troubles, could take no effective counteraction at the time.
The Communist apparatus remains stronger & more effective than at the time of the Geneva Agreements in 1954 where Vietnam was partitioned.
"It was an effective strategy at the time".
It will allow us to remotely deliver the work needed, with the perfection level the client deserves, with the most cost effective approach at the time they require.
