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CLONAL ORIGIN FOR INDIVIDUAL BURKITT TUMOURS
1172 Burkitt’s tumour) was 1-7%, and the crude rate incidence 0-6 and 0-4 per 100,000 of the male and female populations
respectively. Ewing’s sarcoma was not diagnosed. It is certainly true that geographical pathology may provide insight into the aetiological factors of disease. However, before assuming that the Negro race is somewhat protected " from Ewing’s sarcoma, one must explain the findings of the Bristol (England) bone-tumour registry which has been functioning for 25 years and has recorded over 2000 bone tumours; not a single case of Ewing’s sarcoma has been diagnosed. Perhaps, the criteria for diagnosis of this tumour are still somewhat controversial. It is also of interest to note the absence, in Ibadan, of the peak in the incidence of acute leukaemia in children under 5 years of age 1; this peak is also absent in the U.S. Negro. Before postulating genetic influences, however, it should be noted that this peak was absent in England and Wales before 1920,2 and that it may be beginning to emerge in "
non-White children in the United States.3,4 There is a low mortality from leukaemia in countries where death-rates from communicable diseases are still high.I> In Ohio, U.S.A., there is a lower incidence of leukxmia in children of low-income families, irrespective of race.e The evidence would thus suggest that in many populations, the incidence of acute leukaemia in young children is directly related to standards of living and possibly inversely to the presence of multiple infections and infestations. The young child of a low-income family may thus be protected, perhaps immunologically, against leukaemia at an early age. It is, perhaps, significant that in Ibadan, acute leukxmia is not rare in the 5-14 years age-group, suggesting the loss of some " protective " factor. On the other hand, the possible introduction of a carcinogen in young children of upperclass families, or even the early death of the leukaemia-prone child from the numerous infections to which infants in developing countries are exposed, are further possibilities which should be borne in mind. G. M. EDINGTON University of Ibadan, S. P. BOHRER. Nigeria. University of Bristol, J. H. MIDDLEMISS. England.
Po=0-50. If the alternative hypothesis stated Pi =0-45 (or 0-55) and the level of significance were 0-05, the approximate sample size needed to discriminate between the two hypotheses would be 1297. If Pi=O-80 (or 0-20), then, at the same level of significance, a sample size of 35 would be required.
asserts
The sample of size 7 in Dr. Fialkow’s paper is too small to allow for the rejection of the null hypothesis at a level of significance even as high as 0-25 unless the alternative hypothesis PI equals 0-95 (or 0-05). Consequently, we should have to state that there was insufficient evidence to reject the null hypothesis, for this is the meaning of the phrase " accept the null hypothesis ". It is our opinion, therefore, that the findings of Dr. Fialkow of 6 type-B G.-6-P.D. and 1 type-A G.-6-P.D. Burkitt tumours render dubious a hypothesis of Pn 0-50, or, in plain words, the best method to interpret these findings accurately is to obtain additional findings. =
Departments of Pediatrics (Genetics) and Preventive Medicine (Biostatics), University of Pittsburgh School of Medicine, Pennsylvania 15213.
MARK W. STEELE LINCOLN GERENDE.
BIRTH-WEIGHT AND GESTATION PERIOD SIR,-Dr. Widdowson (May 2, p. 901) entitled her review Harmony of Growth. This article contained a fascinating collection of data, which alone made it absorbing reading. However, the concept of harmony involves recognition of an intrinsic pattern or order in the data; without this the information is merely noise. This harmony, unfortunately, was on occasion rather obscured. In particular, we feel we must point out that the data on birth-weight and gestation period were sadly misused. The harmony here (and it is indeed an elegant concept) is simply that the birth-weight shows a remarkably good logarithmic
CLONAL ORIGIN FOR INDIVIDUAL BURKITT TUMOURS SIR,-In your issue of March 28 (p. 677), one of us (M. W. S.) commented on the article by Dr. Fialkow and his colleagues.’ Dr. Fraser (May 2, p. 948) suggests that the remarks in this letter were misleading, since they implied that a null hypothesis was being tested. We should like to make it clear that this letter did not concern itself with a null hypothesis, but rather with the probability of Dr. Fialkow’s data occurring by chance, given the situation as he and his colleagues presented it. This probability is
5.5%. Regarding a statistical test of significance, one has to consider both the null hypothesis and the alternative hypothesis. Also, one must consider the ability of a test to discriminate between these hypotheses. This ability, given a specific value of the level of significance, is dependent on the difference between the values of the two hypotheses and the number of observations. Only if the sample size is sufficiently large will a test detect a small difference between these values. In the present case, the null hypothesis 1. 2. 3. 4. 5. 6. 7.
Edington, G. M., Maclean, C. M. U. Meeting of the International Society of Geographical Pathology, Milan, 1963. Court Brown, W. M., Doll, R. Br. med. J. 1961, i, 981. Rucknagel, D. L. N. Z. Jl Med. 1966, 65, 869. Fraumeni, J. F., Miller, R. W. J. Natn Cancer Inst. 1967, 38, 593. Wld Hlth Org. Chron. 1962, 16, 399. Browning, D., Gross, S. Am. J. Dis. Child. 1968, 116, 576. Fialkow, P. J., Klein, G., Gartlet, S. M., Clifford, P. Lancet, Feb. 21, 1970, p. 384.
relationship to the gestation period (see accompanying figure). In other words, the time required for doubling of the fetal weight is nearly independent of species; from the figures given it may be calculated as about 20 days. Dr. Widdowson’s conclusion from her figures is that " species themselves "; on the contrary, the show that in real terms (mean mitotic interval) the figures growth-rates of different species are extraordinarily similar. The confusion, of course, arises from trying to compare arithmetic means from what is an exponential function.1 vary very much among
1.
Balinski, 1965.
B. I. Introduction to
Embryology; chap.
17.
Philadelphia,
respectively. Ewing’s sarcoma was not diagnosed. It is certainly true that geographical pathology may provide insight into the aetiological factors of disease. However, before assuming that the Negro race is somewhat protected " from Ewing’s sarcoma, one must explain the findings of the Bristol (England) bone-tumour registry which has been functioning for 25 years and has recorded over 2000 bone tumours; not a single case of Ewing’s sarcoma has been diagnosed. Perhaps, the criteria for diagnosis of this tumour are still somewhat controversial. It is also of interest to note the absence, in Ibadan, of the peak in the incidence of acute leukaemia in children under 5 years of age 1; this peak is also absent in the U.S. Negro. Before postulating genetic influences, however, it should be noted that this peak was absent in England and Wales before 1920,2 and that it may be beginning to emerge in "
non-White children in the United States.3,4 There is a low mortality from leukaemia in countries where death-rates from communicable diseases are still high.I> In Ohio, U.S.A., there is a lower incidence of leukxmia in children of low-income families, irrespective of race.e The evidence would thus suggest that in many populations, the incidence of acute leukaemia in young children is directly related to standards of living and possibly inversely to the presence of multiple infections and infestations. The young child of a low-income family may thus be protected, perhaps immunologically, against leukaemia at an early age. It is, perhaps, significant that in Ibadan, acute leukxmia is not rare in the 5-14 years age-group, suggesting the loss of some " protective " factor. On the other hand, the possible introduction of a carcinogen in young children of upperclass families, or even the early death of the leukaemia-prone child from the numerous infections to which infants in developing countries are exposed, are further possibilities which should be borne in mind. G. M. EDINGTON University of Ibadan, S. P. BOHRER. Nigeria. University of Bristol, J. H. MIDDLEMISS. England.
Po=0-50. If the alternative hypothesis stated Pi =0-45 (or 0-55) and the level of significance were 0-05, the approximate sample size needed to discriminate between the two hypotheses would be 1297. If Pi=O-80 (or 0-20), then, at the same level of significance, a sample size of 35 would be required.
asserts
The sample of size 7 in Dr. Fialkow’s paper is too small to allow for the rejection of the null hypothesis at a level of significance even as high as 0-25 unless the alternative hypothesis PI equals 0-95 (or 0-05). Consequently, we should have to state that there was insufficient evidence to reject the null hypothesis, for this is the meaning of the phrase " accept the null hypothesis ". It is our opinion, therefore, that the findings of Dr. Fialkow of 6 type-B G.-6-P.D. and 1 type-A G.-6-P.D. Burkitt tumours render dubious a hypothesis of Pn 0-50, or, in plain words, the best method to interpret these findings accurately is to obtain additional findings. =
Departments of Pediatrics (Genetics) and Preventive Medicine (Biostatics), University of Pittsburgh School of Medicine, Pennsylvania 15213.
MARK W. STEELE LINCOLN GERENDE.
BIRTH-WEIGHT AND GESTATION PERIOD SIR,-Dr. Widdowson (May 2, p. 901) entitled her review Harmony of Growth. This article contained a fascinating collection of data, which alone made it absorbing reading. However, the concept of harmony involves recognition of an intrinsic pattern or order in the data; without this the information is merely noise. This harmony, unfortunately, was on occasion rather obscured. In particular, we feel we must point out that the data on birth-weight and gestation period were sadly misused. The harmony here (and it is indeed an elegant concept) is simply that the birth-weight shows a remarkably good logarithmic
CLONAL ORIGIN FOR INDIVIDUAL BURKITT TUMOURS SIR,-In your issue of March 28 (p. 677), one of us (M. W. S.) commented on the article by Dr. Fialkow and his colleagues.’ Dr. Fraser (May 2, p. 948) suggests that the remarks in this letter were misleading, since they implied that a null hypothesis was being tested. We should like to make it clear that this letter did not concern itself with a null hypothesis, but rather with the probability of Dr. Fialkow’s data occurring by chance, given the situation as he and his colleagues presented it. This probability is
5.5%. Regarding a statistical test of significance, one has to consider both the null hypothesis and the alternative hypothesis. Also, one must consider the ability of a test to discriminate between these hypotheses. This ability, given a specific value of the level of significance, is dependent on the difference between the values of the two hypotheses and the number of observations. Only if the sample size is sufficiently large will a test detect a small difference between these values. In the present case, the null hypothesis 1. 2. 3. 4. 5. 6. 7.
Edington, G. M., Maclean, C. M. U. Meeting of the International Society of Geographical Pathology, Milan, 1963. Court Brown, W. M., Doll, R. Br. med. J. 1961, i, 981. Rucknagel, D. L. N. Z. Jl Med. 1966, 65, 869. Fraumeni, J. F., Miller, R. W. J. Natn Cancer Inst. 1967, 38, 593. Wld Hlth Org. Chron. 1962, 16, 399. Browning, D., Gross, S. Am. J. Dis. Child. 1968, 116, 576. Fialkow, P. J., Klein, G., Gartlet, S. M., Clifford, P. Lancet, Feb. 21, 1970, p. 384.
relationship to the gestation period (see accompanying figure). In other words, the time required for doubling of the fetal weight is nearly independent of species; from the figures given it may be calculated as about 20 days. Dr. Widdowson’s conclusion from her figures is that " species themselves "; on the contrary, the show that in real terms (mean mitotic interval) the figures growth-rates of different species are extraordinarily similar. The confusion, of course, arises from trying to compare arithmetic means from what is an exponential function.1 vary very much among
1.
Balinski, 1965.
B. I. Introduction to
Embryology; chap.
17.
Philadelphia,