# Ch 13 question number 13.9 part (iv)

Discussion in 'CS1' started by SURESH SHARMA, Mar 25, 2020.

1. Dear team
Please note model 1 has 4 parameter , Model 2 has 4 parameter, and model 3 has 8 . How come degree of freedom is 4 for model 1 , 3 for model 2 and zero for model 3.

Regards
Suresh sharma

2. ### John LeeActEd TutorStaff Member

Model 2 has 5 parameters.

3. yes sir , my mistake model 2 has 5 parameter,

please provide the calculation for degree of freedom , model 1=4, model,2 =3, and model 3 =0.
i understand the degree of freedom for chi square ,\
for model 1 its (7-4=3)
for model 2 (4-3=1)
model 3=(3-0=3)

please clarify model 1 degree of freedom =4
model -2 =3
model 3=0

suresh sharma

4. ### John LeeActEd TutorStaff Member

Since the null model (1) has 1 parameter we can see that the original dof before we estimated parameters was 8.
We then subtract the number of parameters from 8 to get the dof for each model.

Null model (1 parameter) dof = 8 - 1 = 7
Model 1 (4 parameters) dof = 8 - 4 = 4
Model 2 (5 parameters) dof = 8 - 5 = 3
Model 3 (8 parameters) dof = 8 - 8 = 0