The total electron content (TEC) contribution to a Parameterized Real-time Ionospheric Specification Model (PRISM) calculation has been studied using protonospheric TEC measurements made by Global Positioning Satellites (GPS). Including the protonosphere proved challenging to both the calibration of GPS measurements and execution of PRISM. Though 46 days of GPS measurements were acquired, only 40 were successfully calibrated, and only 35 of those were used in the study. Data issues such as availability and completeness as well as measurement quality affected 6 of the days used. Calibration was done at Pittsburgh by excluding all measurements below 40.75?? N. latitude cutoff. This latitude produced a plasmaspheric contribution to GPS TEC of 2.5 -- 3.0 TEC units (TECu). Five calibrated days were collected during geomagnetic storm and recovery days, and could not be used in PRISM, reducing the data set to 35 days. Throughout the data, GPS trajectories added up to 3 TECu of error due to low elevation angles and multipath affects. PRISM was found to model the ionosphere with 10.4% to 17% average error, and included a protonospheric contribution result of 1.0 TECu. GPS measurement errors on the order of 3.0 TECu overwhelmed the 17% errors found in PRISM under the same conditions. During quiet periods, the model worked well, with most of the error coming from the GPS TEC measurements.