One state supplied 71% of partial leverage for an ozone by warmth slope in selected western US bird surveys in 1995-2009

We checked how information for an ozone by warmth slope was spread across selected US bird surveys. We reused a signed panel with survey controls and route-observer and region-year effects. One state supplied 70.7% of partial leverage in the West in 1995-2009 and 45.2% in 2010-2024. The largest eastern shares were 8.2% and 8.0%. The inverse sum of squared state shares was 1.92 and 4.22 in the West, compared with 21.96 and 23.65 in the East. This is a concentration measure, not an effective sample size or a test degree of freedom. Removing the largest state increased the early western standard error from 0.184 to 0.553 recorded species per 10 ppb ozone and 2 C warmth. Its estimate stayed negative. This audit shows that a small number of states carry much of the western evidence. It does not prove bias or a false positive. Seasonal exposure error, survey detection, selected coverage and shared source data limit inference. The package has code, the exact panel, state shares, deletion fits, independent projection checks and a figure.

ozone · seasonal warmth · birds · partial leverage · observation bias · cluster inference · information concentration