Shared mailings have always had the reputation of delivering lower response rates than solo mailings.  Our own studies using materials created for companies within the Hamilton House group have (with one interesting exception) confirmed this as true.

Finding that no one else had done any research in this area we initiated a long term study in 1999 to discover why shared mailings regularly resulted in fewer sales than solo mailings.   

You can read what we found by clicking on the links below:

Response rates: an article on the reasons why shared mailings get lower response rates than solo mailings.

Schools and mail: the importance of the school administrator

Highs and lows: HHM experience

Multiple items: how many items to advertise on a leaflet

Headlines: the importance of headines

Price: shared mailings best for lower priced items.

Colour: does colour raise response rates?

Teacher: address your leaflet

Variations: this paper considers the issues that affect response rates in shared mailings to schools.