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Valid oxygen uptake measurements: using high r 2 values with good intentions can bias upward the determination of standard metabolic rate
Author(s) -
Chabot Denis,
Zhang Yangfan,
Farrell Anthony P.
Publication year - 2021
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/jfb.14650
Subject(s) - smoothing , respirometer , function (biology) , linear relationship , statistics , signal (programming language) , plot (graphics) , fish <actinopterygii> , noise (video) , mathematics , metabolic rate , standard error , oxygen , biological system , analytical chemistry (journal) , biology , environmental chemistry , computer science , chemistry , fishery , organic chemistry , evolutionary biology , artificial intelligence , image (mathematics) , programming language , endocrinology
This analysis shows good intentions in the selection of valid and precise oxygen uptake ( M ˙ O 2 ) measurements by retaining only slopes of declining dissolved oxygen level in a respirometer that have very high values of the coefficient of determination, r 2 , are not always successful at excluding nonlinear slopes. Much worse, by potentially removing linear slopes that have low r 2 only because of a low signal‐to‐noise ratio, this procedure can overestimate the calculation of standard metabolic rate (SMR) of the fish. To remedy this possibility, a few simple diagnostic tools are demonstrated to assess the appropriateness of a given minimum acceptable r 2 , such as calculating the proportion of rejected M ˙ O 2 determinations, producing a histogram of the r 2 values and a plot of r 2 as a function of M ˙ O 2 . The authors offer solutions for cases when many linear slopes have low r 2 . The least satisfactory but easiest to implement is lowering the minimum acceptable r 2 . More satisfactory solutions involve processing (smoothing) the raw signal of dissolved oxygen as a function of time to improve the signal‐to‐noise ratio and the r 2 s.