''Consideration Set'' is the list (a set) of specific brands in any product category that are taken seriously (considered) by a consumer during his or her path to purchase (decision-making) period. Consumers are aware of many brands in any given product category, but when the NEED or WANT arises in which they will be purchasing a product from a category, they mentally create a list (the set) of the brands that they are going to consider.
Forming of a ''Consideration Set'' is based on available products options. In general, a consumer's ''Consideration Set'' for any given category is small and may include 5 or less brands. However, it is not a set and, therefore, no consideration if consumers don't have options. It is a fact that when consumers don't have options of brands to select from, their dissatisfaction levels in the brand forced on them is much higher than normal.
For YOUR brand to be placed in a consideration set, a consumer in the path to purchase period (#1) has to know that your brand exists, (#2) must understand your brand's marketing message, and (#3) must have no misperceptions about your brand. Advertising is not necessarily the solution because while it creates brand awareness, the wrong ads can potentially generate confusion or cause misconceptions in the consumer's mind.
If awareness is the front door (lets the consumer know you exist), then credibility is the back door (can let the consumer leave if not closed). It is a fact that even after a brand achieves ''demographic awareness'' (consumers knows where to find it), it will never be seriously considered for purchase until it also achieves ''psychographic credibility.''
First place is important. Generally, the brand that is first considered has the potential of becoming the default brand in the Consideration Set against which the consumer may compare all other brands being added to the set. However, the first-place brand can quickly be replaced once a consumer makes a stronger psychographic connection with another brand -- the one that eventually gets purchased by the consumer.