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164
Radium
groups as to make possible serious error, if too much weight is placed
upon variations of slight degree in the percentages obtained.1 The
committee does not wish to be accused of failing to recognize these facts,
but draws attention to them that no misunderstanding of the conditions
may occur. Such as they are, however, and pending the receipt of additional
records which may tend to overcome this objection by providing
larger number of cases in each group, the results are here reported.
TABULATION OF RHSt'LTS
It was necessary to reject 3S1 records of the total number of 1,210.
The reasons for discarding these records are stated in the Table I.
Thirty-two cases were rejected as they lacked pathological evidence
of the presence of cancer; these cases were, however, all alive and well
more than 3 years after treatment.
Twenty-five cases were rejected because less than 3 years had
elapsed from the time of the last treatment; these cases also were alive
and well.
Five cases, however, were accepted as three year "cures" in which
a period of 3 years had not elapsed after the last treatment with radium.
These were all cases in which the original treatment was given more
than 3 years before, and the later radium treatment was given, without
evidence of recurrence, only as a prophylactic measure. One of these
was a case of hysterectomy with postoperative prophylactic radiatioD.
one. cautery and radium, and three were treated by radium alone.
Kight hundred and twenty-nine cases remain as satisfactory for
study.
TABLE I.—REASON'S FOR RltJFCTINC 381 RECORDS
Total cards received I.2IO
Discards:
Untraccd 159
Xot cancer of cervix 10
Xo treatment 56
Xo pathological diagnosis 32
Under 3 years 25
Re-entries — duplicates 23
1913 and 1020-1021-1922 43
Xo data to classify 13
Otherwise inconclusive 20
— 38l
Satisfactory for study 829
'By ihe courtly of Professor K. B. Wilson of the Harvard School of Public Health the
following explanatory footnote has been added lo Ibis report.
The mathematical formula eomnnnb used by statisticians to Indicate Ihe influence of
chance In determining percentage relations Is e\prc*sed as "standard deviation." Tills terra is
meant to indieat" that chance fluctuation* would be expected to He, at least I wo thirds of the
time, within the assigned limits.
The formula l( as follows: Let N represent the numher of cases recorded and F the fraction
"cured." The "standard deviation" would be \'F n-Fi-rN. Taking the figures from Table III.
as applied to Cl**< l.A: X = 123: F = 3S 123 or .4*. The -standard deviation" would then be
V.2SX.:2-M2^. This Is .04-f.
In terms of percentage this indicates that at least two-thirds of the time the chance, fluctuations
of the !S per cent -ecorded In TaMc III would lie between 21 per cent, and 32 per cent.
The "standard deviation" has been calculated In this way for the percentages given In these
tables and Is noted In the text In reference to those tables where It Is a matter of significance.
Another ionuula "probable error." is sometimes used by statisticians. "Probably error"
Is two-thirds of "standard deviation" and Indicates that one-half of the time the fluctuations
due the "Standard more to chance rigorous deviation" would test. He has within been the used assigned In this flgures. paper in preference lo "probable error" as being