{'fraction_non_alphanumeric': 0.02779783393501805, 'fraction_numerical': 0.0036101083032490976, 'mean_word_length': 4.920940170940171, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
It Is Not So Simple

We are pleased to see that Drs. Cesana and Ulivieri agree with our conclusions regarding the comparison of the single-beam and fan-beam dual-energy X-ray absorptiometry (DXA) instruments. As they point out, our initial examination involved 47 subjects and was confirmed in a second set of 23 subjects. We now have single-beam and fan-beam DXA data for about 250 subjects. When we repeated the Bland–Altman (BA) analyses, the basic results remained unchanged from what we previously reported. Although different values for the coefficients for the translational equations were derived, these values were not statistically different from those we previously reported. That is, the body composition values were not directly “interchangeable” between the two DXA instruments. This should not be too surprising since differences among DXA instruments for bone mineral content and bone mineral density measurements have been known for some time and there are attempts at standardization. As Bland and Altman have pointed out, “It is most unlikely that different methods will agree exactly, by giving the identical results for all individuals.” Furthermore, as they have stated, “It would be amazing if two methods designed to measure the same quantity were not related.” What the BA analysis provides is a measure of the “interchangeability” between methods. That is, if one wants to substitute or replace one method for the other, what would be the limits of agreement? However, an essential criteria (often missed by investigators) must be present in order to use the BA test. That is, the differences between methods must be independent of the average of the two methods. As we clearly noted in Table 2 and showed in Fig. 1, this requirement was not met for any of the DXA body composition compartments. Hence, a direct comparison (calculation of the “degree of agreement”) between the singlebeam and fan-beam DXA measurements would NOT be very meaningful. That is, the data from these two instruments should NOT be pooled without some adjustment. As Cesana and Ulivieri have pointed out in their various quotes from Bland and Altman’s contributions, clinicians are usually not trained as statistical experts. We do not believe that we have used the BA analysis incorrectly in our comparison of the two DXA instruments. We have shown that direct interhangeability was not acceptable. Furthermore, we did not suggest that regression analysis be used to test for interchangeability. Instead, we provided equations (Table 3) that would allow one to adjust (translate) the data for one instrument to the other. This is not a statement of agreement (in fact, it implies disagreement), because there were substantial differences for the younger children. For