Regarding the Sim et al. (2015) paper, the correlation coefficient is found on page 32 and is reported as r(54)=.347. This equation indicates that the correlation coefficient (r) between two variables was 0.347, and the sample size (n) was 54. The parentheses indicate that this is a standardized correlation coefficient, meaning that it has been adjusted for differences in scale between the two variables being correlated. The sample size (n) indicates the number of participants in the study.

I have questions around the above response from a tutor:

1. the sample (as per the start of the study) says there are 56 people in the dataset. So, why was the sample size 54 when looking at the r-value?

2. how do we determine whether the correlation is small, medium or large? What seminal work do we use? is there a table to look at?

3. Table 2 in Cohen's (1992) paper, the first two rows, that is still confusing for me. Let's say that r(54)=.347 is a medium sized positive correlation between hours of intervention and literacy gain, so, because p=.009, II look at the top middle section of the table 2 in Cohen's (1992) paper and find that there should have been 85 people in the sample instead of 54 or 56? Is that right? and if that is right, what does that mean practically?

thank you