Electrostatic coupling is the most common reason readings may be noisy when making high resistance measurements. Electrostatic interference occurs when an electrically charged object is brought near an uncharged object. At low impedance levels, the effects of the interference are not noticeable because the charge dissipates rapidly. However, high resistance materials do not allow the charge to decay quickly, which may result in unstable measurements. Shielding and guarding are both important with high resistance measurements.