I have a sample size of 51 and for my each participant, I have 15 dichotomous variables for vocabulary knowledge (know-not know) and 15 variable for their score for each word. Something like this:

         table     table score
    P1   0              41
    P2   1              55
    P3   0              37  
    P4   1              52

I have 15 different pairs of variables like this and I restructured the data into long format (variables to cases). So now I have 2 main variables as "words" and "scores". I will go for pearson correlation but this time "N" increases to thousands. I have 51 participants, not thousands of people. Is that a problem or normal? I think it is quite reasonable but I am not sure.