Subjects can be randomly assigned to the experimental group and the control group by flipping a coin (both sides are designated as the experimental group and the control group respectively), drawing lots, using a random number table or adopting a systematic randomization method, that is, using ready-made data (such as subject serial number, ID number, medical record card number, work number, student number, etc.). ) alternate.
After random grouping, when the sample size column is large, each group is not completely equal, so experimental research can generally be carried out. When the sample size is small, the number of individuals in each group is quite different, and it needs to be randomly regrouped until the predetermined balance requirement is reached.
Introduction to random grouping:
Randomization means that each observation unit in the group has an equal chance to be selected into the sample and an equal chance to be grouped.
The purpose of random grouping is to make the experimental group and the control group comparable through random balanced interference factors and avoid bias caused by subjective arrangement. Generally used in randomized controlled studies (RCT), yes, you are right, that is, R.
The process of randomization is generally realized by coin toss, lottery, random envelope and center randomization. At present, random envelope and central randomization are widely used. The method of central randomization through telephone, computer and mobile app will be the trend of future randomization, because central randomization can prevent researchers from destroying randomization in some subjective ways.