Counter culture: Causes, extent and solutions of systematic bias in the analysis of behavioural counts

2019 ◽  
Author(s):  
Joel L Pick ◽  
Nyil Khwaja ◽  
Michael A. Spence ◽  
Malika Ihle ◽  
Shinichi Nakagawa
Keyword(s):  
Recent Literature ◽  
Null Model ◽  
Mechanistic Explanation ◽  
Effect Sizes ◽  
Systematic Bias ◽  
Intra Class Correlation ◽  
Counter Culture ◽  
Provisioning Rate ◽  
Parental Provisioning ◽  
Observation Period

We often quantify a behaviour by counting the number of times it occurs within a specific, short observation period. Measuring behaviour in such a way is typically unavoidable but induces error. This error acts to systematically reduce effect sizes, including metrics of particular interest to behavioural and evolutionary ecologists such as R2, repeatability (intra-class correlation, ICC) and heritability. Through introducing a null model, the Poisson process, for modelling the frequency of behaviour, we give a mechanistic explanation of how this problem arises and demonstrate how it makes comparisons between studies and species problematic, because the magnitude of the error depends on how frequently the behaviour has been observed (e.g. as a function of the observation period) as well as how biologically variable the behaviour is. Importantly, the degree of error is predictable and so can be corrected for. Using the example of parental provisioning rate in birds, we assess the applicability of our null model for modelling the frequency of behaviour. We then review recent literature and demonstrate that the error is rarely accounted for in current analyses. We highlight the problems that arise from this and provide solutions. We further discuss the biological implications of deviations from our null model, and highlight the new avenues of research that they may provide. Adopting our recommendations into analyses of behavioural counts will improve the accuracy of estimated effect sizes and allow meaningful comparisons to be made between studies.

Interpreting Statistical Significance and Meaningfulness in Adapted Physical Activity Research

1998 ◽  
Vol 15 (2) ◽  
pp. 103-118 ◽  
Author(s):  
Vinson H. Sutlive ◽  
Dale A. Ulrich
Keyword(s):  
Physical Activity ◽  
Sample Size ◽  
Recent Literature ◽  
Statistical Significance ◽  
Effect Sizes ◽  
Significance Tests ◽  
Adapted Physical Activity ◽  
Research Designs ◽  
Alpha Level ◽  
Research Findings

The unqualified use of statistical significance tests for interpreting the results of empirical research has been called into question by researchers in a number of behavioral disciplines. This paper reviews what statistical significance tells us and what it does not, with particular attention paid to criticisms of using the results of these tests as the sole basis for evaluating the overall significance of research findings. In addition, implications for adapted physical activity research are discussed. Based on the recent literature of other disciplines, several recommendations for evaluating and reporting research findings are made. They include calculating and reporting effect sizes, selecting an alpha level larger than the conventional .05 level, placing greater emphasis on replication of results, evaluating results in a sample size context, and employing simple research designs. Adapted physical activity researchers are encouraged to use specific modifiers when describing findings as significant.

scholarly journals Gait differences in patients with multiple sclerosis who have low and high levels of disability

2019 ◽  
Author(s):  
John J. Fraser ◽  
Jeannie B. Stephenson
Keyword(s):  
Multiple Sclerosis ◽  
Analysis Of Variance ◽  
Cycle Time ◽  
Correlation Coefficients ◽  
Effect Sizes ◽  
Intra Class Correlation ◽  
Gait Impairment ◽  
Gait Characteristics ◽  
Disability Group

AbstractBackgroundMultiple Sclerosis (MS) often results in gait impairment and disability.ObjectiveTo investigate differences in spatiotemporal gait characteristics of people with MS who have low versus high levels of disability. Between trial and inter-limb consistency and the association of gait variables with level of disability were also investigated.MethodsParticipants with MS who had either low-disability [n=7; 3 females; EDSS mean: 2.7±0.5, range 2.0-4.5; BMI=26.9±6.6] or high-disability [n=11; 6 females; EDSS mean: 2.7±0.5, range 6.0-6.5; BMI=27.8±1.5) performed 2 trials of self-selected walking on an instrumented walkway. Differences in group, limb, and group by limb interactions were assessed using analysis of variance, independent-measures t-tests, and Cohen’s d effect sizes (ES). Between-trial consistency of gait were assessed with intra-class correlation coefficients (2, k).ResultsParticipants in the high disability group had increased step time (ES=0.8), cycle time (ES=0.8), and ambulation time (ES=1.2) while taking shorter strides (ES=0.9) and more steps at a slower rate (ES=1.1). The high disability group demonstrated less between-trial consistency for 69% of gait variables when compared to the low disability group.ConclusionPeople with MS who have high levels of disability walk differently and with less consistency than those with lower levels of disability.

Can changes in provisioning by parent birds account for seasonally declining patterns of offspring recruitment?

2011 ◽  
Vol 89 (10) ◽  
pp. 921-928 ◽  
Author(s):  
L.E. Bortolotti ◽  
V.B. Harriman ◽  
R.G. Clark ◽  
R.D. Dawson
Keyword(s):  
Environmental Conditions ◽  
Food Abundance ◽  
Tachycineta Bicolor ◽  
Life History Strategies ◽  
Tree Swallows ◽  
Proximate Mechanisms ◽  
Audio Recordings ◽  
Provisioning Rate ◽  
Parental Provisioning ◽  
Seasonal Decline

Declining reproductive success among individuals that breed later in the season occurs in numerous taxa and is particularly well-documented in birds. Principal ideas advanced to explain this pattern, the date and parental quality hypotheses, consider the ultimate causes of this phenomenon and have received much attention; however, proximate mechanisms have not been clearly elucidated. Parental provisioning could mediate a seasonal decline in nestling fitness. We delayed hatch dates and manipulated brood sizes of Tree Swallows ( Tachycineta bicolor (Vieillot, 1808)) to assess the ability of parents to compensate for deteriorating environmental conditions and increased demands of more chicks. We measured provisioning rates using audio recordings of nestlings begging. Brood size was the best predictor of provisioning frequency, with parents feeding larger broods more frequently than smaller ones. Delayed hatching did not reduce provisioning rate despite declining food abundance. Date and food abundance were unrelated to provisioning rate, suggesting no seasonal change in the quantity of food nestlings receive. However, provisioning frequency was informative about life-history strategies of Tree Swallows, showing that late breeders incurred the costs of deteriorating environmental conditions rather than passing these costs on to their offspring.

scholarly journals Effect of lumbar laminectomy on spinal sagittal alignment: a systematic review

2021 ◽  
Author(s):  
Juho Hatakka ◽  
Katri Pernaa ◽  
Juho Rantakokko ◽  
Inari Laaksonen ◽  
Mikhail Saltychev
Keyword(s):  
Lumbar Lordosis ◽  
Pelvic Tilt ◽  
Sagittal Alignment ◽  
Surgical Techniques ◽  
Vertical Axis ◽  
Effect Sizes ◽  
Decompressive Surgery ◽  
Systematic Bias ◽  
Sagittal Vertical Axis ◽  
Spinal Sagittal Alignment

Abstract Purpose Positive spinal sagittal alignment is known to correlate with pain and disability. The association between lumbar spinal stenosis and spinal sagittal alignment is less known, as is the effect of lumbar decompressive surgery on the change in that alignment. The objective was to study the evidence on the effect of lumbar decompressive surgery on sagittal spinopelvic alignment. Methods The Cochrane Controlled Trials Register (CENTRAL), Medline, Embase, Scopus and Web of Science databases were searched in October 2019, unrestricted by date of publication. The study selection was performed by two independent reviewers. The risk of systematic bias was assessed according to the NIH Quality Assessment Tool. The data were extracted using a pre-defined standardized form. Results The search resulted in 807 records. Of these, 18 were considered relevant for the qualitative analysis and 15 for the meta-synthesis. The sample size varied from 21 to 89 and the average age was around 70 years. Decompression was mostly performed on one or two levels and the surgical techniques varied widely. The pooled effect sizes were most statistically significant but small. For lumbar lordosis, the effect size was 3.0 (95% CI 2.2 to 3.7) degrees. Respectively, for pelvic tilt and sagittal vertical axis, the effect sizes were − 1.6 (95% CI .2.6 to − 0.5) degrees and − 9.6 (95% CI − 16.0 to − 3.3) mm. Conclusions It appears that decompression may have a small, statistically significant but probably clinically insignificant effect on lumbar lordosis, sagittal vertical axis and pelvic tilt.

scholarly journals Reliability (or Lack Thereof) of Smartphone-Delivered Visual Dot Probe Attention Bias Indices

2020 ◽  
Author(s):  
Nur Hani Hani Zainal ◽  
Nicholas C. Jacobson
Keyword(s):  
Anxiety Disorder ◽  
Attention Bias ◽  
Effect Sizes ◽  
Dot Probe ◽  
Facilitation Effect ◽  
Internal Reliability ◽  
Intra Class Correlation ◽  
Retest Reliability ◽  
Reliability Estimates ◽  
Intra Class Correlation Coefficient

Cognitive bias theories posit that generalized anxiety disorder (GAD) and social anxiety disorder (SAD) are entwined with attention bias (AB) toward threats, commonly indexed by faster response time (RT) on threat- congruent (vs. incongruent) trials on the visual dot probe (VDP). Moreover, although smartphone VDP assessments have been developed, their psychometric properties are understudied. This study thus aimed to assess the retest-reliability and internal reliability of 6 smartphone-delivered VDP AB and related indices in persons with and without GAD and SAD (Global ABI, Disengagement Effect, Facilitation Bias, AB Variability [ABV], Congruent RT, Incongruent RT). Participants (n = 819) completed a five-trial smartphone-delivered VDP for at least one session. Of these, 294, 151, 94 participants completed 2, 5, and 12 sessions, respectively, across 2 weeks. Across 5 trials per session, Global ABI, Disengagement Effect, and Facilitation Bias had low reliability estimates (mean intra-class correlation coefficient [ICC] = 0.01–0.51; split-half reliability [r] = 0.01–0.18). Conversely, retest-reliability and internal reliability were good for Congruent RT and Incongruent RT (mean ICCs = 0.72–0.97; r = 0.37–0.92). Across 2, 5, and 12 sessions, poor retest-reliability and internal reliability estimates were consistently observed for all 6 AB and related indices. Compared to non-anxious controls, Global ABI and Facilitation Effect were stronger for those with GAD (d = 0.16–0.21) and SAD (d = 0.20–0.25), with negligible-to-small effect sizes. Theoretical and clinical implications, alongside suggestions to improve the reliability of smartphone VDP apps, are discussed.

scholarly journals Use of score-based tests in IRT Models

2015 ◽  
Author(s):  
◽  
Ting Wang
Keyword(s):  
Item Response Theory ◽  
Measurement Invariance ◽  
Item Response ◽  
Likelihood Function ◽  
Null Model ◽  
Theoretical Background ◽  
Model Parameters ◽  
Systematic Bias ◽  
Response Theory ◽  
Item Response Theory Models

Measurement invariance is a fundamental assumption in item response theory models, where the relationship between a latent construct (ability) and observed item responses are of interest. Violation of this assumption would render the scale misinterpreted or cause systematic bias against certain groups of people. While a number of methods have been proposed to detect measurement invariance violations, they all require definition of problematic model parameters and respondent grouping information in advance. However, these "locating" pieces of information are typically unknown in practice. As an alternative, this dissertation focuses on a family of recently-proposed tests based on stochastic processes of casewise derivatives of the likelihood function (i.e., scores). These score-based tests only require estimation of the null model (when measurement invariance assumption holds), with problematic subgroups of respondents and model parameters being identified in a factor-analytic, continuous data context. In this dissertation, I aim to generalize these tests to item response theory models for categorical data. The tests' theoretical background and implementation are detailed. The tests' ability to identify problematic subgroups and model parameters is studied via simulation. An empirical example involving the tests is also provided. In the end, potential applications and future development are discussed.

scholarly journals Results from the NASA GSFC and LaRC Ozone Lidar Intercomparison: New Mobile Tools for Atmospheric Research

2015 ◽  
Vol 32 (10) ◽  
pp. 1779-1795 ◽  
Author(s):  
John T. Sullivan ◽  
Thomas J. McGee ◽  
Russell DeYoung ◽  
Laurence W. Twigg ◽  
Grant K. Sumnicht ◽  
...  
Keyword(s):  
Tropospheric Ozone ◽  
The United States ◽  
Systematic Bias ◽  
Differential Absorption ◽  
Atmospheric Research ◽  
Nasa Goddard Space ◽  
Goddard Space Flight Center ◽  
Precision And Accuracy ◽  
Langley Research Center ◽  
Observation Period

AbstractDuring a 2-week period in May 2014, the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center Tropospheric Ozone Differential Absorption Lidar (GSFC TROPOZ DIAL) was situated near the NASA Langley Research Center (LaRC) Mobile Ozone Lidar (LMOL) and made simultaneous measurements for a continuous 15-h observation period in which six separate ozonesondes were launched to provide reference ozone profiles. Although each of these campaign-ready lidars has very different transmitter and receiver components, they produced very similar ozone profiles, which were mostly within 10% of each other and the ozonesondes. The observed column averages as compared to the ozonesondes also agree well and are within 8% of each other. A robust uncertainty analysis was performed, and the results indicate that there is no statistically significant systematic bias between the TROPOZ and LMOL instruments. With the extended measurements and ozonesonde launches, this intercomparison has yielded an in-depth evaluation of the precision and accuracy of the two new lidars. This intercomparison is also the first (to the best of the authors’ knowledge) reported measurement intercomparison of two ground-based tropospheric ozone lidar systems within the United States.

scholarly journals Hierarchical fear: parental behaviour and corticosterone release mediate nestling growth in response to predation risk

2020 ◽  
Author(s):  
Devin R. de Zwaan ◽  
Kathy Martin
Keyword(s):  
Predation Risk ◽  
Life Stage ◽  
Cold Temperatures ◽  
Predator Cues ◽  
Nestling Growth ◽  
Nestling Development ◽  
Provisioning Rate ◽  
Parental Provisioning ◽  
Wing Growth ◽  
Perceived Predation Risk

AbstractNestling development, a critical life-stage for altricial songbirds, is highly vulnerable to predation, particularly for open-cup nesting species. Since nest predation risk increases cumulatively with time, rapid growth may be an adaptive response that promotes early fledging. However, greater predation risk can reduce parental provisioning rate as a risk aversion strategy and subsequently constrain nestling growth, or directly elicit a physiological response in nestlings with adaptive or detrimental effects on development rate. Despite extensive theory, evidence for the relative strength of these effects on nestling development in response to prevailing predation risk and the underlying mechanisms remain unclear. For an alpine population of horned lark (Eremophila alpestris), we elevated perceived predation risk (decoys/playback) during the nestling stage to assess the influence of predator cues and parental care on nestling wing growth and the glucocorticoid hormone corticosterone. We used piecewise path analysis to test a hypothesized causal response structure composed of direct and indirect pathways. Nestlings under greater perceived predation risk reduced corticosterone and increased wing growth, resulting in an earlier age at fledge. This represented both a direct response that was predator-specific, and an indirect response dependent on parental provisioning rate. Parents that reduced provisioning rate most severely in response to predator cues had smaller nestlings with greater corticosterone. Model comparisons indicated the strongest support for a directed, causal influence of corticosterone on nestling wing growth, highlighting corticosterone as a potential physiological mediator of the nestling growth response to predation risk. Finally, cold temperatures prior to the experiment constrained wing growth closer to fledge, illustrating the importance of considering the combined influence of weather and predation risk across developmental stages. We present the first study to separate the direct and indirect effects of predation risk on nestling development in a causal, hierarchical framework that incorporates corticosterone as an underlying mechanism and provides experimental evidence for an adaptive developmental response to predation risk in ground-nesting songbirds.

scholarly journals Histochemistry today: Detection and location of single molecules

2017 ◽  
Author(s):  
Carlo Pellicciari
Keyword(s):  
In Situ Hybridization ◽  
Quantitative Assessment ◽  
Recent Literature ◽  
Single Molecules ◽  
High Specificity ◽  
Mechanistic Explanation ◽  
Lectin Histochemistry ◽  
Cell Functions ◽  
Molecular Maps

Especially in the latest years, histochemical investigations have progressively been oriented toward the visualization and quantitative assessment of single molecules, thanks to the availability of stains, reactions and procedures allowing to detect in situ proteins, or carboydrates or nucleic acid sequences with high specificity. This is evident from the recent literature, where in the large majority of the published articles immunohistochemistry, lectin histochemistry or fluorescence in situ hybridization were used as experimental methodologies. Since in biomedical research it is crucial to specifically label and localize molecules there, where they exert their structural roles and activities, histochemistry will continue to provide scientists the most appropriate tools for tracing molecular maps suitable for reaching a mechanistic explanation of cell functions in tissues.

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