The phenomenon that may operate when subjects are selected on the basis of extremely high or extremely low pre-test scores is called

Older adults with transitional developmental concerns get little assistance in which of the following services

Statistical test of a non-directional hypothesis is

Consider the following statements :

1. Acquired immune deficiency syndrome seems to have begun in Central Africa
2. AIDS is transmitted through the Human Immunodeficiency Virus (HIV)
3. A person may test HIV-seropositive (HIV +) but be free of AIDS
4. Intensive community-based interventions aimed at risk population will be effective.

Of the statements :

The best technique for selecting a representative sample is

The process of building organizations that ensure the effectiveness of work teams and of their organisations is called