Defining confidence interval for reduced chi-square test?

Hi,

I have observed data and predicated data from different models.I did the reduced chi-square test between the observed and model data using the below equation

reduced chi-square = sum{(obs-model)^2/sigma^2}/v; where v is the degree of freedom and sigma is the variance of the observed data.

I got the reduced chi-square value from 0-500, as we know that the reduced chi-square value <= 1 indicates that the extent of the match between observations and estimates is in accord with the error variance. So I suggest the models which are within 0-1 reduced chi-square value. But I want to defined the confidence interval for the reduced chi-square of my data. I want to find the models which are within 95% confidence interval. Does anyone tell me how I can define the confidence interval for the reduced chi-square of my data. Thanks in advance.