Hi Marty, this doesn’t sound quite right. Can you describe what you mean by:
This seems contradictory. Do you actually mean you just have one parameter (the duration for a particular stimulus), which has 90 values?
How do they vary? i.e. do you just have a single trial, which can contain just one of 90 possible values, or 90 trials, with one value each? We really need a proper description of this to help you out. Think what would be required for a Methods section of a journal article.