From 1999 to 2009 the majority of all pregnant women were invited to participate through a postal invitation.
Pregnant women were invited to participate through a postal invitation after they signed up for routine ultrasound examination in their local hospital.
Practices were invited to take part by postal invitation following a publicity campaign using a modified viral marketing technique involving sequential non-specific PANDAs post cards ('PANDAs are coming') to 'pique' interest, followed by increasingly informative flyers (figure 1).
Expecting mothers were invited to join the study through postal invitation in connection with a routine ultrasound examination offered to all pregnant women in Norway at gestation weeks 17 18, and 42.7% agreed to participate.
Patients who are participants in the UK Primary Sjögren's Syndrome Registry (UKPSSR) 28 and have consented to be approached about further studies will be invited to take part in this study via a postal invitation.
The study participants will be contacted by email or postal mail and invited to participate.
A random sample of the registered GPs in a given postal code were invited to participate by fax, and called 3 5 days later by one of the three trained peers.
For the qualitative study reported here, a pragmatic sample consisting of all participants living in the Otago and Southland regions of New Zealand who had reported an MSD in the follow-up postal survey were invited to participate in a single face-to-face qualitative interview in 2008.
In brief, all practices within the Champlain region were invited to participate in IDOCC through a postal or fax invitation.
All individuals in Hordaland county, Norway, born between 1953 and 1957 (being 40 45 years old at the time of investigation) were invited by postal mail to participate in the study (n = 29 400).
