I am wanting to sum four means I have (food intake measured in Kcal) as I need to total food intake vs the Kcal for each type of food. I have the M and SD of Kcal for each food type for both the intervention and control group, so my question is, how do I then calculate a total SD of total food intake for each group?
See these examples of similar previous forum questions
https://www.researchgate.net/post/How-to-combine-standard-deviations-for-three-groups
https://math.stackexchange.com/questions/2971315/how-do-i-combine-standard-deviations-of-two-groups
See these links:
https://www.researchgate.net/post/How_do_I_combine_mean_and_standard_deviation_of_two_groups
https://www.researchgate.net/post/How-to-combine-standard-deviations-for-three-groups
https://www.westgard.com/lesson35.htm
https://stats.stackexchange.com/questions/25848/how-to-sum-a-standard-deviation
(if you have a list of numbers in excel, you may add +-. But you might add a separate sd. the former means it is the same. it happens when you plot a graph)
I think it is better to calculate the standard deviation of all groups and then average the standard deviations of these groups, this can provide a better insight.
- Badges
- Science topic
- Similar topics
- Mathematics
- Statistics