The MOST USEFUL dimensions for segmenting markets:?

[WB]

are geographic and demographic dimensions.
are brand familiarity and consumption patterns.
are social class.
are benefits sought.
depend on what product-market one is segmenting.

[Jim Coe]

I believe that the most important market segmentation is based on market niches and the niche's:
* Needs
* Desires
* Fears

So, yes - it depends on the market. And for finding less competitive markets (where the small time operator can thrive) one needs to segment each market into niches, not full markets.

Example: Market = parenting, niche = first-time new mothers
(This is not actual research data, just stuff I made up as examples)
Needs:
* Child care info
* Health products (e.g. colic cure)
* Infant products
* Child care services
* Mother/Infant fashions

Desires:
* Security
* Stability
* Time for infant care and bonding
* Retain her figure and looks
* To stay in touch with with friends/family/work, in spite of lack of time

Fears:
* Not a good enough mother
* Losing good looks or health, staying in shape
* Infant health problems
* Losing touch with the rest of her life
* Relationship with husband changing

Notice that there are strong emotional and subconscious themes here and understanding those is a big help in market research and in planning the eventual campaign.

Hope this helped you...
_jim coe