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1 <br />ROCKY ;FLATS SOIL PLUTONIIJM27+z°° SURVEYS FROM ] 970 TO 1991 <br />' The change in scale highlights the extent of the differences in the levels of plutonium792°0 <br />between Sector 2 and all other sectors. These are not subtle differences. Sectors 1 and <br />sectors 3 through 7 data are many multiples below Sector 2 data. Sectors 8 through 13 <br />values are a magnitude or more below Sector 2. <br />' At this scale the levels represented by the "box" portion of the graph, the 25th to 75th <br />percentiles, for Sector 7 stands out, having higher plutonium""200 levels than other <br />sectors (excluding Sectors 1 and 2). Only Sector 6's levels overlaps with Sector 7. An <br />' examination of the individual values for Sector 6 show the overlap in data caused by <br />values measured prior to 1975. <br />Sector 6 overlaps with the other Boxes for sectors 3, 4, 5, 8, 9, 10, ] 1, 12, 13. The <br />median for sector's 3, 4, 5, and 6 are slightly above the means for sectors 8 through 13. <br />There may be some significance to the differences. The "boxes" for sectors 11, 12 and 13 <br />' are very tight even at this scale, meaning very little deviation in the measured values. <br />' The examination of the data and box plots raises the question if some significant change occurred <br />in the data after 1974. Were there some activities or mechanisms in affect prior to 1975 that <br />resulted in significantly different data from 1970-1974 and 1975-1991? Descriptive statistics and <br />' plots of 1975 to 1991 data were examined separately, then compared to the entire data set to see <br />if any difl erences could be determined and if they are significant. <br />CI <br />t! <br /> <br /> <br /> <br />r <br /> <br /> 12 <br /> <br /> <br />