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# Block Randomization in Clinical Trials: Video Tutorial in Microsoft Excel

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:

1. Number the participants from 1 to n.
2. 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
3. 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.
4. Now allot a block to each group e.g. Group 1 = PT, Group 2 = TP, Group 3 PT and so on.
5. And now insert RAND function it the next column and filter to sort the random numbers which are inserted as shown in the video.
6. Allot the treatment groups to volunteers/ patients according to the randomization done. 