The is a method in which neither the research participants nor the researchers know whether the participants are getting the treatment or a placebo.

The double-blind study is a method in which neither the research participants nor the researchers know whether the participants are getting the treatment or a placebo. Is a tool of the scientific method used to prevent research results can be influenced by the placebo effect or observer bias.

changes in factors like average income and preferences can cause an entire demand curve to shift right or left. this causes a higher or lower quantity to be demanded at a given price. demand curves relate the prices and quantities demanded assuming no other factors change. it is important for consumers to know this information, because it is crucial for them to know what they can afford and can't afford. i hope this .