The following specifies information about the data. 


Fig 5b data

The 1st column: squre of the measured displacement (x^2) in m^2
The 2nd column: error in the sqare of measured displacement (x^2) in m^2
The 3rd column: measured duffing shift in angular resonance frequency delta_omega_m in rad/s
The 4th column: error in measured duffing shift in angular resonance frequency delta_omega_m in rad/s