42 Section 3: Numeric Functions
Correcting Accumulated Statistics
If you discover that you have entered data incorrectly, the accumulated statistics
can be easily corrected. If one value of an (x, y) data pair is incorrect, you must
delete and re-enter both values.
1. Key the incorrect data pair into the X- and Y-registers.
2. Press ´w to delete the incorrect data.
*
3. Key in the correct values for x and y.
4. Press z.
Alternatively, if the incorrect data point or pair is the most recent one entered
and z has been pressed, you can press ´K ´w to remove the
incorrect data.
Example: After keying in the preceding data, Voltz found new information
indicating that the coal output for the last data pair should have been 1.946
instead of 1.943. Use w to remove the statistical data that were accumulated
as a result of using the older, incorrect data pair; then key in the correct data
pair.
Keystrokes Display
1.943v
6.713w
1.943
4.000
Keys in the data pair we
want to replace and
deletes the pair's
unwanted statistics.
Number of pair entries
then drops to four.
1.946v
6.713 z
1.946
5.000
Keys in and accumulates
the replacement data
pair. Number of pairs
accumulated is again
five.
Retain these statistics in your calculator for use in the following examples.
*
Note: Although
´w
can be used to delete an erroneous (x, y) pair, it will not delete any
rounding errors that may have occurred when the statistics of that pair were added into
registers R
1
through R
5
. Consequently, subsequent results may be different than they
would have been if the erroneous pair had not been entered with
z
. However, the
difference will not be serious unless the erroneous pair has a magnitude that is enormous
compared with the correct pair; and in such a case it may be wise to start over again and
re-enter the data carefully.
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