Power calculations to get sample size needed to run an experiment

by Charlotte87
Tags: calculations, experiment, power, sample, size
Charlotte87 is offline
Jan24-14, 07:45 AM
P: 22
Hi everyone!

I am writing a paper in development/experimental economics concerning how household bargaining power (i.e. how much say the husband and wife has about how to spend household income) affect how much money is spent on children. I am going to conduct an experiment and is now in the phase of doing some power calculations in order to see how large sample I need. Unfortunately, I am having some problems doing these power calculations. I understand their purpose and everything, but I do not really see how I should use STATA to do the correct calculations.

I am doing a between-subject design with three treatments. In each treatment the money available will be varying. So, I think I need to do power calculations where I compare proportions since I will be comparing the share of money spent on children in each treatment group.

Even though I have three treatments, I will only compare two-and-two treatments. I will compre treatment 1 with treatment 2, treatment 1 with treatment 3 and treatment 2 with treatment 3. So far I have used the following command in STATA:

sampsi 0.1 0.3, power(0.9)

The significance level is then automatically 0.05, and 0.1 and 0.3 is proportions (i.e here the share of money spent on children). Does this make sense??

I have made a table comparing proportions from 0 to 1 (with a 0.1 intervals) and made a table, but I am still not sure whether my method is correct.
Phys.Org News Partner Social sciences news on Phys.org
Study finds law dramatically curbing need for speed
Newlyweds, be careful what you wish for
Can new understanding avert tragedy?

Register to reply

Related Discussions
How to calculate how big of a sample size is needed for the Central Limit Theorem? Set Theory, Logic, Probability, Statistics 2
Motor size calculations needed Mechanical Engineering 0
Determining sample size needed to test hypothesis Set Theory, Logic, Probability, Statistics 1
Determining sample size needed to test hypothesis Calculus & Beyond Homework 6
sample size needed for power of a study Set Theory, Logic, Probability, Statistics 5