\magnification=\magstep2

$$
   x(t)  \quad = \quad a + bt 
$$

$$
   x(t)  \quad = \quad c + dt + et^2 
$$

$$
   \chi^2 \quad = \quad \sum_i {{  { ({\rm data}_i - {\rm model}_i)}^2  }\over{ \sigma_i^2 } }
$$

$$
   \chi^2 \quad = \quad  {{  { (0.00 - 1.54)}^2  }\over{ (0.5)^2 } } 
                  \quad + \quad \dots
$$


$$
   \chi^2 \quad = \quad  {{  { (0.00 - 0.26)}^2  }\over{ (0.5)^2 } } 
                  \quad + \quad \dots
$$

$$
   {\rm reduced \ } \chi^2 \quad = \quad {  {\chi^2} \over 
          { {\rm number\ of\ degrees\ of\ freedom } } }
$$





\bye

