This is a video tutorial on how to do block randomization in clinical trials/ studies. This is a very common way of randomization in research studies.
I have explained mainly of block randomization of a group of 2 in Microsoft excel. I have also mentioned briefly about block randomization with a group of 4.
Steps to be followed:
- Number the participants from 1 to n.
- Divide each participant into groups starting from 1. Easiest is to divide into groups of 2. As the possible combinations are easy to know. e.g. In a group of 2, the possible combinations of blocks are PT & TP. (P = Placebo, T = Test). This can be changed depending on a number of groups and number of volunteers. In case of group of 4, number of possible blocks are 6. e.g. A & B are groups then possible blocks are
ABBA ABAB BBAA ABAB BAAB BABA
- Then divide the total number of volunteers/ patients by number in each group. i.e. n/2 or n/4 in my examples. You will now get a total number of groups.
- Now allot a block to each group e.g. Group 1 = PT, Group 2 = TP, Group 3 PT and so on.
- And now insert RAND function it the next column and filter to sort the random numbers which are inserted as shown in the video.
- Allot the treatment groups to volunteers/ patients according to the randomization done.