I am going to run a quantitative experiment but I need my participants to come over and do some tasks in front of me. since I cannot recruit more than 40 participant (economic issues) and at the same time I need several data, I am going to ask each participant to go through the same task with different inputs. For example, I will ask the first participant to go through the installation of 10 different applications. At first I was thinking if I recruit 40 participant each going through 10 installation process, I would have 400 data points. However, I did not consider the correlation among the answers taken from one participant.
My question is: What is the best way to determine the number of participants for my experiment considering the fact that the responses from each participant are correlated with each other? Is there any reference or formula I can get the answer of my question?