Problems with chemotaxis

I am working on C.elegans chemotaxis. i seem to have run into a problem. I am trying to reproduce this paper
Unfortunately i am not able to replicate it. Just for standardization purpose. I am just working with naive and 1 h starved worms.
Although my starved worms have shown a slight increase (as reported), i am getting a chemotaxis index of 0.4-0.5 instead of the reported 0.28-0.30.
WHat might be the problem?


There can be lot of issues.
For example, the temparature at which you running the assays, the amount of worms you are using in each experiment, how you treat the worms from very beginning,
how you wash them before the start of experiment, etc etc…

To get an exact CI index as reported in the original paper is quite difficult initially and you need to optimize a lot of things.