so4_tacoma[,1]
year_tacoma[,2]
year_factor(year)
station_tacoma[,3]
station_factor(station)
tacoma.frame_data.frame(so4=so4,year=year,station=station)
tacoma.aov_aov(so4~year*station, data=tacoma)
summary.lm(tacoma.aov)