Convergent Validity of Satellite and Secchi Disk Measures of Water Clarity in Hedonic Models

The depleted population of belugas (Delphinapterus leucas) inhabiting the St Lawrence estuary, Canada, was monitored by periodic photographic aerial surveys. In order to correct counts made on aerial survey film and to obtain an estimate of the true size of the population, the diving behaviour and the visibility from the air of these animals was studied. A Secchi-disk turbidity survey in the belugas’ summer range showed that water clarity varied between 1.5 m and 11.6 m. By studying aerial photographs of sheet-plastic models of belugas that had been sunk to different depths below the surface, we found that models of white adults could be seen down to about the same depth as a Secchi disk, but no deeper. Smaller models of dark-grey juveniles could only be seen down to about 50% of Secchi-disk depth. By observing groups of belugas from a hovering helicopter and recording their disappearances and re-appearances, it was found that they were visible for 44.3% of the time, and that an appropriate correction for single photographs would be to multiply the photographic count by about 222% (SE 20%). For surveys in which there was overlap between adjacent frames, the estimated correction would be 209% (SE 16%). This correction factor was slightly conservative and gave an estimate of the true size of the population, based on a single survey, of 1,202 belugas (SE 189) in 1997. An estimate for 1997 based on smoothing 5 surveys 1988–1997 was 1,238 (SE 119).

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Secchi Disk Depth Estimation from China’s New Generation of GF-5 Hyperspectral Observations Using a Semi-Analytical Scheme

Remote Sensing ◽

10.3390/rs12111849 ◽

2020 ◽

Vol 12 (11) ◽

pp. 1849 ◽

Cited By ~ 1

Author(s):

Yao Liu ◽

Chenchao Xiao ◽

Junsheng Li ◽

Fangfang Zhang ◽

Shenglei Wang

Keyword(s):

Depth Estimation ◽

Water Clarity ◽

Absolute Error ◽

High Spectral Resolution ◽

Secchi Disk ◽

Secchi Disk Depth ◽

Analytical Scheme ◽

Turbid Waters ◽

Inland Water Bodies ◽

New Generation

Water clarity, commonly measured as the Secchi disk depth ( Z s d ), is an important parameter that depicts water quality in aquatic ecosystems. China’s new generation Advanced HyperSpectral Imager (AHSI) on board the GF-5 satellite has significant potential for applications of more accurate water clarity estimation compared with existing multispectral satellite imagery, considering its high spectral resolution with a 30-m spatial resolution. In this study, we validate the semi-analytical model with various Quasi-Analytical Algorithms (QAA), including Q A A V 5 , Q A A V 6 , Q A A L 09 and Q A A M 14 , for the AHSI images with concurrent in situ measurements in four inland water bodies with a Z s d range of 0.3–4.5 m. The semi-analytical method with Q A A V 5 can yield the most accurate Z s d predictions with approximated atmospheric-corrected remote sensing reflectance. For 84 concurrent sampling sites, the estimated Z s d had a mean absolute error (MAE) of 0.35 m, while the mean relative error (MRE) was 25.3%. Specifically, the MAEs of estimated Z s d were 0.22, 0.46, and 0.24 m for Z s d of 0.3–1, 1–3, and 3–4.5 m, respectively. The corresponding MREs were 33.1%, 29.1% and 6.3%, respectively. Although further validation is still required, especially in terms of highly turbid waters, this study indicates that AHSI is effective for water clarity monitoring.

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Cladoceran body length and Secchi disk transparency in northeastern U.S. lakes

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f03-124 ◽

2003 ◽

Vol 60 (12) ◽

pp. 1477-1486 ◽

Cited By ~ 13

Author(s):

Richard S Stemberger ◽

Eric K Miller

Keyword(s):

Chlorophyll A ◽

Body Length ◽

Nutrient Loading ◽

Size Structure ◽

Light Attenuation ◽

Water Clarity ◽

Secchi Disk ◽

Particulate Carbon ◽

Secchi Disk Transparency ◽

Organic Particles

Mean cladoceran body length of 59 northeastern U.S. lakes was estimated from functional groups that broadly define taxonomic, body size, and grazing potential. Multiple regression of body length, color, and chlorophyll a or total phosphorus against Secchi disk transparency explained 72% and 83% of the variation across lakes, respectively. Analysis that included body length, color, and particulate carbon, a proxy for light backscattering and absorption by suspended organic particles, explained 85% of the variance in transparency. Body length was as important a predictor of water clarity as chemical factors. Furthermore, body length was significantly correlated to temporal variation in transparency within lakes. Because cladocerans primarily filter organic particles in size ranges having high light attenuation efficiencies, body length was consistently more strongly correlated to transparency than to chlorophyll a. Monitoring cladoceran body length should help to distinguish changes in lake transparency due to nutrient loading from changes that reflect fish population size structure and predation intensity on zooplankton. This simple size index can greatly increase the interpretative value of Secchi transparency observations to lake managers.

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Development of a Solar-Powered IoT-Based Instrument for Automatic Measurement of Water Clarity

Sensors ◽

10.3390/s20072051 ◽

2020 ◽

Vol 20 (7) ◽

pp. 2051 ◽

Cited By ~ 1

Author(s):

Tuan Ngoc Pham ◽

Anh Pham Huy Ho ◽

Tuong Van Nguyen ◽

Ha Minh Nguyen ◽

Nhu Huynh Truong ◽

...

Keyword(s):

Light Intensity ◽

Water Column ◽

Secchi Depth ◽

Measurement Data ◽

Automatic Measurement ◽

Regression Function ◽

Weather Conditions ◽

Water Clarity ◽

Secchi Disk ◽

Pass Through

Water clarity is the most common indicator of water quality. The purpose of the study was to develop an instrument which can automatically measure water clarity in place of manual measurement by Secchi disk. The instrument is suspended by buoys at the water surface and uses solar energy to measure the light intensity of LED bulbs after passing through a water column; the result is then converted to Secchi depth by using a regression function. Measurement data are stored in a cloud server so that mobile users can access via an Internet connection. Three experiments were conducted to examine the instrument performance: (i) to ensure light intensity of the LED bulbs is strong enough to pass through the water column; (ii) to determine the regression relationship between the measured light intensity of the instrument and Secchi depth; and (iii) to evaluate the coefficient of variation (CV) of the measured water clarity when using our instrument and a conventional Secchi disk. Experiment results show that the measured values of light intensity are stable with the average CV = 5.25%. Moreover, although there are slight differences between the Secchi depth measured by our instrument and those measured by Secchi disk, the measurements by our instrument can efficiently replace the measurements by conventional Secchi disk, which can be affected by weather conditions as well as by human subjectivity.

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CODEM Instrument

GeroPsych ◽

10.1024/1662-9647/a000100 ◽

2014 ◽

Vol 27 (1) ◽

pp. 23-31 ◽

Cited By ~ 4

Author(s):

Anne Kuemmel (This author contributed eq ◽

Julia Haberstroh (This author contributed ◽

Johannes Pantel

Keyword(s):

Convergent Validity ◽

Interrater Reliability ◽

Discriminant Validity ◽

Assessment Tool ◽

Intraclass Correlation ◽

Well Being ◽

Communication Behavior ◽

People With Dementia ◽

Pearson's R ◽

Pearson’S R

Communication and communication behaviors in situational contexts are essential conditions for well-being and quality of life in people with dementia. Measuring methods, however, are limited. The CODEM instrument, a standardized observational communication behavior assessment tool, was developed and evaluated on the basis of the current state of research in dementia care and social-communicative behavior. Initially, interrater reliability was examined by means of videoratings (N = 10 people with dementia). Thereupon, six caregivers in six German nursing homes observed 69 residents suffering from dementia and used CODEM to rate their communication behavior. The interrater reliability of CODEM was excellent (mean κ = .79; intraclass correlation = .91). Statistical analysis indicated that CODEM had excellent internal consistency (Cronbach’s α = .95). CODEM also showed excellent convergent validity (Pearson’s R = .88) as well as discriminant validity (Pearson’s R = .63). Confirmatory factor analysis verified the two-factor solution of verbal/content aspects and nonverbal/relationship aspects. With regard to the severity of the disease, the content and relational aspects of communication exhibited different trends. CODEM proved to be a reliable, valid, and sensitive assessment tool for examining communication behavior in the field of dementia. CODEM also provides researchers a feasible examination tool for measuring effects of psychosocial intervention studies that strive to improve communication behavior and well-being in dementia.

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The Hierarchical Model of Exercise Dependence

Journal of Individual Differences ◽

10.1027/1614-0001/a000172 ◽

2015 ◽

Vol 36 (4) ◽

pp. 247-257 ◽

Cited By ~ 1

Author(s):

Gayatri Kotbagi ◽

Laurence Kern ◽

Lucia Romo ◽

Ramesh Pathare

Keyword(s):

Factor Analysis ◽

Confirmatory Factor Analysis ◽

Physical Exercise ◽

Exploratory Factor Analysis ◽

Convergent Validity ◽

Large Population ◽

Assessment Tools ◽

Negative Consequences ◽

Confirmatory Factor ◽

Preliminary Version

Abstract. Physical exercise when done excessively may have negative consequences on physical and psychological wellbeing. There exist many scales to measure this phenomenon. The purpose of this article is to create a scale measuring the problematic practice of physical exercise (PPPE Scale) by combining two assessment tools already existing in the field of exercise dependency but anchored in different approaches (EDS-R and EDQ). This research consists of three studies carried out on three independent sample populations. The first study (N = 341) tested the construct validity (exploratory factor analysis); the second study (N = 195) tested the structural validity (confirmatory factor analysis) and the third study (N = 104) tested the convergent validity (correlations) of the preliminary version of the PPPE scale. Exploratory factor analysis identified six distinct dimensions associated with exercise dependency. Furthermore, confirmatory factor analysis validated a second order model consisting of 25 items with six dimensions and four sub-dimensions. The convergent validity of this scale with other constructs (GLTEQ, EAT26, and The Big Five Inventory [BFI]) is satisfactory. The preliminary version of the PPPE must be administered to a large population to refine its psychometric properties and develop scoring norms.

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Detection of Malingered Neurocognitive Dysfunction Among Patients with Acquired Brain Injuries

European Journal of Psychological Assessment ◽

10.1027/1015-5759/a000154 ◽

2013 ◽

Vol 29 (4) ◽

pp. 253-262 ◽

Cited By ~ 6

Author(s):

Omer Hegedish ◽

Dan Hoofien

Keyword(s):

Response Bias ◽

Concurrent Validity ◽

Convergent Validity ◽

Brain Injuries ◽

Neurocognitive Dysfunction ◽

Word Memory Test ◽

Malingered Neurocognitive Dysfunction ◽

Compensation Seeking ◽

Seeking Behavior ◽

Verbal Test

The Word Memory Test (WMT) is one of the most sensitive forced-choice tests available designed to evaluate negative response bias (NRB). Presently there is no valid verbal test designed to evaluate NRB for Hebrew-speaking patients. The aims of the present study were to validate the response bias measures of the WMT among Hebrew-speaking patients with acquired brain injuries and to reveal the malingering base rate among Israeli patients involved in compensation-seeking. Participants were 112 patients. The Test of Memory Malingering (TOMM) was used for convergent validity and injury related variables were used for concurrent validity. A translated version of the WMT had high split-half reliability. Regarding convergent validity, WMT effort measures had high positive correlations with the TOMM. Moreover, based on TOMM cutoff scores for classification, the WMT had reasonable classification rates. Regarding concurrent validity, multivariate logistic regression revealed that failure in the WMT was significantly predicted by normal brainscans and involvement in compensation-seeking behavior. The baserate of probable malingering was 34%. These findings emphasize the universality of the WMT in detecting NRB and establishing a malingered neurocognitive dysfunction baserate among Israeli patients involved in compensation-seeking.

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