set output 'chisquare_a.ps' 
set term postscript color enhanced  
set grid 
set key top left 
set xlabel 'time (microseconds)' 
set ylabel 'position of electron (cm)' 
set title 'An electron moves through a cloud chamber' 
plot [-1:6][-5:55]  'electron.dat' index 0     using ($1):($2):($3)  t ''     with yerrorbars lc 1 lw 3  ,  1.54 + 9.69*x t 'linear fit'     with lines lc 3 lw 2  ,  0.26 + 11.6*x - 0.38*x*x t 'quadratic fit'     with lines lc -1 lw 1  
set output 
quit 
