We compare the 145 to 300 km altitude variation of the measured photoelectron flux in the 13 to 18 eV, 28 to 34 eV, and 50 to 55 eV energy regions with the variations expected from theory. There is a strong linear relationship between the measured photoelectron flux and the attenuation of the solar EUV flux at these energies. Therefore, the photoelectron flux is sensitive to changes in the solar zenith angle, neutral density scale height, and total neutral density. However, contrary to previous assertions, the photoelectron flux at most energies is not sensitive to the relative densities of the neutral constituents. In addition, we obtain excellent agreement between theory and measurement. By using the concept of photoelectron production frequencies, we reduce the usually complex evaluation of the local equilibrium photoelectron flux to a trivial calculation so that the steps in the calculation can be readily verified.