Single-blind study: the control group was given Kuanxin Pill (a non-toxic, harmless and ineffective substance). In this way, both groups of patients don't know whether they are taking new drugs or soothing pills, so the psychological influence or mental effect is the same. At this time, the results of the two groups of patients will be compared, and the effect of the new drug can be obtained. However, it is a pity that even if researchers adopt the method of Kuanxin Pill, there may still be errors.

Double-blind study: No matter the patient as the experimental object or the medical staff as the experimental participant (or observer), they don't know who (double-blind) the new drug was given to and who Kuanxin Pill was given to. In this way, medical staff will observe the two results of patients taking drugs and taking Kuanxin pills more objectively, so the explanation of the actual effect of new drugs will be more accurate and scientific.

Extended data:

Experimental research, also known as experimental research, is a method of collecting direct data. Select the appropriate group, control the related factors by different means, and test the difference of reaction between groups. Researchers use the principles and methods of scientific experiments, the main purpose of which is to establish the causal relationship between variables. The general practice is that researchers put forward a tentative hypothesis of causality in advance and then test it through experimental operations. It is a comparative research method, which evaluates its effect on one or more variables through the changes of one or more variables.