HI,
I am using Windows XP and R version 2.9.2. I have a data frame written by R
similar to the following:
Lab_ID Analysis_Soil Results -4MAD -2.5MAD
+2.5MAD +4MAD
55003 Calcium-2008-116 900 961 1121.5
1656.5 1817
55003 Calcium-2008-117 3321 2175 2380.5
3065.5 3271
55003 Calcium-2008-118 3342 3155 4019
6899 7763
55003 Calcium-2008-119 1664 1005.6 1147.92 1622.32
1764.64
55003 Calcium-2008-120 2570 1880 2072 2712
2904
Previously, I took this table and finished my analysis in Excel using
Excel's "=if" function. However, I am sure it can be done in R. What I want
to do is set up a new data.frame with a new column for Accuracy Flags
(a_flag) as shown below.
Lab_ID Analysis_Soil Results -4MAD -2.5MAD
+2.5MAD +4MAD a_flag
55003 Calcium-2008-116 900 961 1121.5
1656.5 1817 **L
55003 Calcium-2008-117 3321 2175 2380.5
3065.5 3271 **H
55003 Calcium-2008-118 3342 3155 4019
6899 7763 *L
55003 Calcium-2008-119 1664 1005.6 1147.92 1622.32
1764.64 *H
55003 Calcium-2008-120 2570 1880 2072 2712
2904
For each row I need to compare the "Results" submitted by the labs to the
four "MAD" columns. If the Results are less than -4.0 MAD units from the
median, labs are flagged "**L" (very low). For results greater than +4.0 MAD
units, labs are flagged "**H" (very high). Likewise for -2.5 MAD and +2.5
MAD (*L and *H respectively). As shown in the last row, labs are not flagged
for results within -2.5 MAD to +2.5 MAD units.
Can anyone get me started on how to look at each row and compare the
"Results" variable with each of the four "__MAD" variables and then writing
the appriate flag for Results exceeding -2.5 MAD to +2.5 MAD units from the
median?
Thanks,
Jerry Floren
Minnesota Department of Agriculture
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