Nonsensical and biased correlation due to pooling heterogeneous samples

Hassler, Uwe; Thadewald, Thorsten

doi:10.1111/1467-9884.00365

Cited by 41 publications

(41 citation statements)

References 16 publications

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“…In order to avoid nonsensical and biased correlation due to the pooling of heterogeneous samples (Hassler & Thadewald, 2003), the relationships between experimental measurements, hawthorn materials and extraction techniques are represented graphically using scatter plots ( Fig. 1a-j).…”

Section: In Vitro Antioxidant Activity -Total Phenol Content Dpph Anmentioning

confidence: 99%

Influence of extraction technique on the anti-oxidative potential of hawthorn (Crataegus monogyna) extracts in bovine muscle homogenates

et al. 2014

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Section: In Vitro Antioxidant Activity -Total Phenol Content Dpph Anmentioning

confidence: 99%

Influence of extraction technique on the anti-oxidative potential of hawthorn (Crataegus monogyna) extracts in bovine muscle homogenates

et al. 2014

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“…When ignored, these could obscure meaningful correlations and blur subgroup differences in task performance (White, Lott, & de Wit, 2006;Mohr, Krummenacher, et al, 2005;Kosslyn et al, 2002;Mattay et al, 2000;Mehta et al, 2000;Kimberg, DʼEsposito, & Farah, 1997;Fleming, Bigelow, Weinberger, & Goldberg, 1995). Furthermore, as Hassler and Thadewald (2003) pointed out, pooling data from heterogeneous samples bears the risk to produce misleading results due to "mean value artifacts" (see also the recent illustration by Hadzi-Pavlovic (2007). One source of individual variability in DA responsiveness may be genetically determined (Goldberg et al, 2003;Egan et al, 2001;Weinberger et al, 2001), and potential interactions between such genetic predispositions and an individualʼs attitude toward the paranormal are currently explored (Raz, Hines, Fossella, & Castro, 2008).…”

Section: Further Issuesmentioning

confidence: 99%

Dopamine, Paranormal Belief, and the Detection of Meaningful Stimuli

Kempler

Möhr

Haker³

et al. 2010

Journal of Cognitive Neuroscience

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Dopamine, paranormal belief, and the detection of meaningful stimuliKrummenacher, P; Mohr, C; Haker, H; Brugger, P Krummenacher, P; Haker, H; Brugger, P (2010 Abstract ■ Dopamine (DA) is suggested to improve perceptual and cognitive decisions by increasing the signal-to-noise ratio. Somewhat paradoxically, a hyperdopaminergia (arguably more accentuated in the right hemisphere) has also been implied in the genesis of unusual experiences such as hallucinations and paranormal thought. To test these opposing assumptions, we used two lateralized decision tasks, one with lexical (tapping left-hemisphere functions), the other with facial stimuli (tapping right-hemisphere functions). Participants were 40 healthy righthanded men, of whom 20 reported unusual, "paranormal" experiences and beliefs ("believers"), whereas the remaining participants were unexperienced and critical ("skeptics"). In a between-subject design, levodopa (200 mg) or placebo administration was balanced between belief groups (double-blind procedure). For each task and visual field, we calculated sensitivity in the placebo group. Criterion analyses revealed that believers favored false alarms over misses, whereas skeptics displayed the opposite preference. Unexpectedly, under levodopa, these decision preferences were lower in both groups. We thus infer that levodopa (1) decreases sensitivity in perceptual-cognitive decisions, but only in skeptics, and (2) makes skeptics less and believers slightly more conservative. These results stand at odd to the common view that DA generally improves signal-to-noise ratios. Paranormal ideation seems an important personality dimension and should be assessed in investigations on the detection of signals in noise. ■

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“…6 It has been established that severely biased linear relationships can occur owing to sample heterogeneity. 13 From a physiological viewpoint, it could be argued that the curtailed ability of the original 20mMST model to predict treadmill Vo 2max values might be attributed to differences in the exercise modes utilised in the validation procedures (that is, shuttle running v forward running). Findings from recent investigations suggested that Vo 2max during the 20mMST is significantly higher compared to a treadmill test.…”

mentioning

confidence: 99%

Enhancing the efficacy of the 20 m multistage shuttle run test

Flouris

2005

Br J Sports Med

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Objective: Maximal oxygen uptake (Vo 2max ) of 44 ml kg 21 min 21 is an accepted criterion (Vo 2CR ) below which health and fitness for young male adults may be compromised. New algorithms validated for Vo 2CR screening using the 20 m multistage shuttle run test (20mMST) were developed. Methods: Vo 2max was assessed in 110 males using a stationary gas analyser in a treadmill test (TT) and in 40 of these subjects using a portable gas analyser in the 20mMST. Vo 2max predicted from the 20mMST in 70 subjects was used for cross validation. Two equations predicting Vo 2max during 20mMST (EQ MST ) and TT (EQ TT ) were developed. Results: Significant energy cost variance (EC V ) was detected between TT and 20mMST (p,0.001), correlated significantly with subject height, and was a significant predictor of Vo 2max differences between TT and 20mMST. statistical screening methodology such as calculating receiver operating characteristics (ROC) curves has not been employed hitherto. The ROC curve analysis is extensively used in epidemiology to provide a graphic means for assessing the accuracy of a diagnostic instrument. 3 The difficulty in adopting ROC curves in sports medicine is mainly attributed to the fact that most outcome measures are in continuous format. However, these biomarkers can be dichotomised using dummy variables according to clinically accepted critical values Q and defined positive or negative if the test outcome measure is greater or lesser than Q. For instance, a maximal oxygen uptake (Vo 2max ) of 44 ml kg 21 min 21 for young male adults (18-29 years of age) has been generally accepted as a criterion (Vo 2CR ) below which both health and fitness may be compromised. The 20 m multistage shuttle run test (20mMST) 6 represents an acceptable field assessment tool for CF, and has been repeatedly employed in different health 7 8 and fitness 9 settings. However, the popularity of the 20mMST is mainly attributed to its practical use for simultaneous measurement of large groups of individuals. Studies evaluating its accuracy in predicting laboratory Vo 2max have reported contradictory results.9-11 More importantly, the efficacy (that is, the extent to which a specific procedure produces a valid classification of data in relation to established criteria) of the original 20mMST model in screening for CF remains unknown.From a statistical standpoint, the limited accuracy of the 20mMST may be attributed to the repeated measures design used in the original study. 6 It is well known that the inherent dependency of within-subject observations can reduce the power of prediction models.12 Concurrently, it seems tenable that the theoretical basis of the original 20mMST model may be further compromised by the use of generally large and heterogeneous samples in the validation procedures.6 It has been established that severely biased linear relationships can occur owing to sample heterogeneity. 13From a physiological viewpoint, it could be argued that the curtailed ability of the original 20mMST model to predict treadmill Vo 2...

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Nonsensical and biased correlation due to pooling heterogeneous samples

Cited by 41 publications

References 16 publications

Influence of extraction technique on the anti-oxidative potential of hawthorn (Crataegus monogyna) extracts in bovine muscle homogenates

Influence of extraction technique on the anti-oxidative potential of hawthorn (Crataegus monogyna) extracts in bovine muscle homogenates

Dopamine, Paranormal Belief, and the Detection of Meaningful Stimuli

Enhancing the efficacy of the 20 m multistage shuttle run test

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