The phrase "a far less effective" is correct and usable in written English.
It can be used when comparing the effectiveness of two or more things, indicating that one is significantly less effective than another.
Example: "The new marketing strategy proved to be a far less effective approach than the previous one."
Alternatives: "much less effective" or "significantly less effective".
Until the development of the new vaccine, public health officials had to rely on a far less effective polysaccharide vaccine that protected people only for two to three years and did not prevent transmission of the bacteria.
We conclude that salary differentials are a far less effective tool for retaining teachers with strong preservice qualifications than for retaining other teachers in schools with high proportions of minority students.
By contrast intraperitoneal inoculation of virus containing cellfree extracts of FBJ-MSV sarcomata was a far less effective immunization procedure.
She said that she would not trust Mr Galloway to "deliver a pizza", far less effective policies.
Because what I loved as a kid is far less effective to my adult sense.
But legal experts say that such a defense may well be far less effective in a Federal case.
Too many community safety partnerships, which bring together the police, local authorities and other agencies, are bogged down in a meetings culture and far less effective than assumed in Whitehall.
I had to step down to a much cheaper, yet far less effective medication and it just didn't cut it.
This leads to a perverse situation, highlighted by the HPA India report, in which patients who can afford private health care can receive fentanyl patches – a more expensive but far less effective form of pain relief – while poorer Indians are denied the cheap, efficient opiate-derived solutions plentiful in their own country.
Therefore to try to teach people about "wowness" in a classroom way would be far less effective, maybe futilely so, than to invite a target audience into one's planning from the very start, to help define, from distinctive individual perspectives (the audience came from around the world), what "wowness" meant to them and why.
Now that it has dissipated into a network, it has proved far less effective.
