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If a sample has 'n' observation x1x_1, x2x_2 ............. xnx_n with 'm' constraints on these values then degree of freedom of sample statistic is:

Solution

✅ Correct Option: 4

The degree of freedom represents the number of values that are free to vary after accounting for constraints.

When a sample has nn observations: x1,x2,...,xnx_1, x_2, ..., x_n with mm constraints on these values, each constraint restricts one value from varying freely.


Consider an example with 5 numbers where their sum must equal 20 (1 constraint).

The first 4 numbers can be chosen freely: 2, 3, 4, 5

The 5th number must be 6 to satisfy the constraint (sum = 20)

Only 4 numbers are free to vary = 5 - 1 = 4 degrees of freedom


Each constraint reduces the freedom by 1 since it "locks" one value that would otherwise be free to vary.

With nn observations and mm constraints:

Degree of Freedom =n−m= n - m


Examples:

10 values with no restrictions: 10−0=1010 - 0 = 10 degrees of freedom

10 values with mean fixed: 10−1=910 - 1 = 9 degrees of freedom

10 values with mean and variance fixed: 10−2=810 - 2 = 8 degrees of freedom


Therefore, the degree of freedom of the sample statistic is n−mn - m.

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