randomize
Random grouping is the process of assigning subjects to different treatment groups according to the principle of randomization. Randomly grouping can ensure that every subject has the same chance to be assigned to the experimental group or the control group, so that some clinical characteristics and interference factors that may affect the experimental results are evenly distributed among the groups and are comparable. The results are not interfered and influenced by non-processing factors, which effectively avoids the prejudice of various artificial objective factors and/or subjective factors on the research results and makes the results more authentic and reliable.
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The basic idea of random grouping
Although random grouping seems simple, it is often misunderstood and misused in the specific operation of clinical trials. For example, some researchers put the subjects into the experimental group and the control group alternately according to the grouping order of the subjects. This grouping method can easily be mistaken for random grouping, but in fact, the grouping of one subject is determined, and the grouping of the next subject is also determined, so it is impossible to guarantee that the subjects have the same opportunity to enter different treatment groups. So what method is generally used to realize random grouping?
Random grouping can be done by drawing lots, tossing coins or dice, but it is more scientific and reliable to group by random numbers. The basic idea is as follows:
1. Generate corresponding random numbers for each research object included in the clinical trial.
2. Sort the random numbers from small to large (or from large to small);
3. According to the preset sample size of each treatment group, the corresponding sample numbers are selected in random numerical order and assigned to different treatment groups.
In clinical trials, subjects are often grouped one by one, and it is impossible for researchers to wait until the subjects have collected enough data before grouping for experiments. Therefore, before the start of the study, the subjects should be randomly assigned to different treatment groups according to the grouping order and corresponding random numbers, and the grouping should be concealed. Once the subjects meet the selection criteria and are included in the study, they can directly enter the corresponding grouping to start the experiment according to the predetermined grouping scheme.
Random grouping SPSS operation
I. Research examples
Suppose a research plan includes 330 subjects, which are numbered according to the order in which the subjects entered the group. After entering the group, the subjects were randomly divided into three groups, A, B and C, and given different treatment measures, in which A was a placebo group, B was a conventional drug group and C was a combination drug group, with 1 10 people in each group.
Second, set a random number seed.
In order to make the results of random grouping repeatable, we need to set a random seed in advance before grouping. Generally speaking, we use the time of random grouping to determine random seeds. For example, in this example, we set the random number seed as 20 1804 15, and the operation steps are as follows.
1. Click Transform → Random Number Generator.
2. Select Set Starting Point to set the starting point in the initialization box of the active generator, and select Fixed Value to set the fixed value. Fill in 20 1804 15 in the value box, and click OK to finish the setting.