The number of children involved in sporting clubs varies enormously across different primary schools, depending on such factors as the size of the school, the socio-economic background of the students, the amount of interest the teachers have in sport and whether or not the school has an active sports program.

The National Netball League (NNL) want to encourage more children to join a junior netball club. They think that providing schools with netballs will increase the number of children playing the game. Sixty primary schools were randomly selected to take part in a study of sports participation. The schools are randomly allocated to one of two groups, a control group and an experimental group. Half of the schools in each group have an active sports program and half do not.

In March, schools in the experimental group are presented with 20 new netballs. The presentation is made by a well-known NNL player who talks to the children about her NNL career. In October the schools in the experimental group are asked to survey their students and to record the number of children who are members of a junior netball club. Schools in the control group are asked to survey their students in October and to record the number of children who are members of a netball club.

After the data is collected in October, the researchers compare the number of netball memberships in the schools who were given the netballs to the number of memberships in schools who were not provided with netballs.

At the end of the study, the data is analysed and the NNL researchers find that the primary schools given the netballs have significantly higher numbers of Junior Netball Club members than those primary schools not provided with netballs.

1) Is this study experimental or observational

2)What research design has been used here

3)Is there any bias in the sample selection evident in the description of this study?