The relationship between w and Cramers V is: w = V * SquareRoot(r-1)
where "r" is the smaller of the number of rows and number of columns
(mind that in this context "df" does not mean degrees of freedom of
the Chi square statistic). As you already know (from the presentation
with r=2), w=0.1 may be assumed as "small", 0.3 as "medium", 0.5 as
Martin A Volker (2006): Reporting effect size estimates in school psychology research.
Psychology in the Schools, Vol. 43(6), 653-672.