Who among the following was the first man to describe 'Null Hypothesis'?

Which of the following measures may be adopted for bringing a change in the behaviour and complete modification of the client's philosophy of life?

Psychologists face an interesting problem not shared by physicists and chemists. Human subjects are very sensitive to hints from an experimenter about what is expected of them, is called . . . . . . . .

Consider the following statements
1. Field experiments and quasi experiments are conducted in natural setting
2. Field experiments and quasi experiments study real life problems
3. Field experiments study imaginary problems
Select the correct answer from the options given below:

Situational variables include