Our FAR121 OPS SPECS require the duty dispatchers to make runway analysis for departure, arrival and alternate airports. We carry a Runway Analysis Manual aboard to double check the figures. We never get involved in "computing" "effective runway length." The RAM includes data for each runway with varying temperatures, wind, slope, wet/dry, Anti Skid, QNH corrections, second segment climb limits, and respective max or reduced (assumed temperature) power settings.