No worries! I am approaching this debate in a collaborative spirit. I may have been misunderstanding you as well.
What I see when I examine the second graph you have shown, again in isolation, is that it does indeed look very much like the results of the “shifted normal” model you described earlier. Or rather, of that process happening twice, with a sort of temporary tapering off around 1940. Although if I’m understanding right, the earlier pre-60s part is pure extrapolation. This graph clearly fits your and Natalia’s hypothesis and not SMTM’s, we see nothing of particular significance around 1980.
As you say, the next question becomes how to decide which to put more weight on. Do we like the statistical heft of Komlos and Brabec, or do we think they’re just using fancy statistics to erase a crucial feature of the raw data? I don’t know how to arbitrate that question. But I would be sympathetic to an interpreter who said they were convinced by the sophisticated statistical model and viewed the apparent “elbow” in the raw data as more likely an artifact than a real feature of the true trend, and I’m sure Komlos and Brabec know much better than me what they’re about.
My way of proceeding would be to say “looking at the raw data, it does look like there’s a sharp change around 1980, but that might be an artifact. Looking at a sophisticated curve-fitting model of similar data, that feature vanishes. We might put 80% weight on the sophisticated modeling and 20% on the raw data, and note that the raw data itself isn’t so incompatible with a “shifted normal” interpretation, maybe 70⁄30.” Overall, I’m inclined to put maybe 85% credence in the “shifted normal” interpretation in which there was no big event in obesity around 1980, and 15% credence that a real ” elbow feature” is being obscured by the statistical smoothing.
No worries! I am approaching this debate in a collaborative spirit. I may have been misunderstanding you as well.
What I see when I examine the second graph you have shown, again in isolation, is that it does indeed look very much like the results of the “shifted normal” model you described earlier. Or rather, of that process happening twice, with a sort of temporary tapering off around 1940. Although if I’m understanding right, the earlier pre-60s part is pure extrapolation. This graph clearly fits your and Natalia’s hypothesis and not SMTM’s, we see nothing of particular significance around 1980.
As you say, the next question becomes how to decide which to put more weight on. Do we like the statistical heft of Komlos and Brabec, or do we think they’re just using fancy statistics to erase a crucial feature of the raw data? I don’t know how to arbitrate that question. But I would be sympathetic to an interpreter who said they were convinced by the sophisticated statistical model and viewed the apparent “elbow” in the raw data as more likely an artifact than a real feature of the true trend, and I’m sure Komlos and Brabec know much better than me what they’re about.
My way of proceeding would be to say “looking at the raw data, it does look like there’s a sharp change around 1980, but that might be an artifact. Looking at a sophisticated curve-fitting model of similar data, that feature vanishes. We might put 80% weight on the sophisticated modeling and 20% on the raw data, and note that the raw data itself isn’t so incompatible with a “shifted normal” interpretation, maybe 70⁄30.” Overall, I’m inclined to put maybe 85% credence in the “shifted normal” interpretation in which there was no big event in obesity around 1980, and 15% credence that a real ” elbow feature” is being obscured by the statistical smoothing.