You should Select Intensity Correction when comparing sources with continuum spectra (e.g., incandescent sources).

Please note that this correction will only work properly if you are using the optical fiber attachment to your Vernier-branded spectrometer. See https://www.vernier.com/products/accessories/optical-fiber-cables/ for the correct optical fiber for your spectrometer.

DO NOT use the Intensity Correction if you are comparing emission lines from discharge tubes.

Spectral Analysis has not yet implemented a way to turn on Intensity Correction. This feature can only be used in Logger Pro or LabQuest.

See also
Can I do blackbody experiments with the Vernier or Ocean Optics Spectrometers?