I have been looking at Chen and Thissen LD chi square calculations done in IRTPRO and I compared it to MIRT package. The values are different as in IRTPRO they are subtracting the degree of freedom from chi square value and then dividing it by 2* degree of freedom square root.

What I am confused is when I want to assess whether my questions have local dependency should I look at the chi square critical table or z-score table ??

Moreover, in IRTPRO guide they mentioned that they don't consider values like 2 and 3 to be high and  values above 10 are local dependent.

"Because the standardized LD X2 statistic is only approximately standardized, and is known to be based on a statistics with a longtailed (X2) distribution, we do not consider values larger than 2 or 3 to be large. Rather, we consider values larger than 10 large,indicating likely LD; values in the range 5-10 lie in a gray area, and may either indicate LD or they may be a result of sparseness in the underlying table of frequencies."

Note: I have 14 questions with 126 responses and my data is dichotomous

and using LD chi square test my degree of freedom will be 1