Intrasubject Variability in Power Reflectance

2014 ◽  
Vol 25 (05) ◽  
pp. 441-448 ◽  
Author(s):  
Defne Abur ◽  
Nicholas J. Horton ◽  
Susan E. Voss
Keyword(s):  
Standard Deviation ◽  
Repeated Measurements ◽  
Ear Canal ◽  
Mean Power ◽  
Deep Insertion ◽  
Left And Right ◽  
The Mean ◽  
Standard Deviations ◽  
The Individual ◽  
The Right

Background: Power reflectance measurements are an active area of research related to the development of noninvasive middle-ear assessment methods. There are limited data related to test-retest measures of power reflectance. Purpose: This study investigates test-retest features of power reflectance, including comparisons of intrasubject versus intersubject variability and how ear-canal measurement location affects measurements. Research Design: Repeated measurements of power reflectance were made at about weekly intervals. The subjects returned for four to eight sessions. Measurements were made at three ear-canal locations: a deep insertion depth (with a foam plug flush at the entrance to the ear canal) and both 3 and 6 mm more lateral to this deep insertion. Study Sample: Repeated measurements on seven subjects are reported. All subjects were female, between 19 and 22 yr old, and enrolled at an undergraduate women’s college. Data Collection and Analysis: Measurements on both the right and left ears were made at three ear-canal locations during each of four to eight measurement sessions. Random-effects regression models were used for the analysis to account for repeated measures within subjects. The mean power reflectance for each position over all sessions was calculated for each subject. Results: The comparison of power reflectance from the left and right ears of an individual subject varied greatly over the seven subjects; the difference between the power reflectance measured on the left and that measured on the right was compared at 248 frequencies, and depending on the subject, the percentage of tested frequencies for which the left and right ears differed significantly ranged from 10% to 93% (some with left values greater than right values and others with the opposite pattern). Although the individual subjects showed left-right differences, the overall population generally did not show significant differences between the left and right ears. The mean power reflectance for each measurement position over all sessions depended on the location of the probe in the ear for frequencies of less than 1000 Hz. The standard deviation between subjects' mean power reflectance after controlling for ear (left or right) was found to be greater than the standard deviation within the individual subject’s mean power reflectance. The intrasubject standard deviation in power reflectance was smallest at the deepest insertion depths. Conclusions: All subjects had differences in power reflectance between their left and right ears at some frequencies; the percentage of frequencies at which differences occurred varied greatly across subjects. The intrasubject standard deviations were smallest for the deepest probe insertion depths, suggesting clinical measurements should be made with as deep an insertion as practically possible to minimize variability. This deep insertion will reduce both acoustic leaks and the effect of low-frequency ear-canal losses. The within-subject standard deviations were about half the magnitude of the overall standard deviations, quantifying the extent of intrasubject versus intersubject variability.

The Effects of Ethyl Alcohol on a Driver's Driving Skill, Visual Perception, Risk Acceptance, Choice Reaction Times and Information Processing Rates

1974 ◽  
Vol 18 (2) ◽  
pp. 116-116
Author(s):  
Helmut T. Zwahlen
Keyword(s):  
Information Processing ◽  
Standard Deviation ◽  
Visual Perception ◽  
Reaction Times ◽  
Driving Skill ◽  
Alcohol Condition ◽  
The Mean ◽  
Risk Acceptance ◽  
Standard Deviations ◽  
Choice Reaction Times

Twelve subjects (20–37 years old) were tested in the laboratory and eleven out of these were also tested in a car in the field, first under a no alcohol condition and then under an alcohol condition (approximately 0.10% BAC). In the laboratory the subjects simple and choice reaction times for two uncertainty modes were measured and their information processing rates (3 bits unsertainty) were determined. In the field the subjects driving skill for driving through a gap with 20 inches total clearance at 20 MPH was measured, as well as their static visual perceptual capabilities and risk acceptance decisions for a 46 feet viewing distance using psychophysical experimental methods. Based upon the driving skill measure (standard deviation of centerline deviations in the gap), the mean of the psychometric visual gap perception function and the mean of the psychometric gap risk acceptance function, the “Safety Distance” and the “Driver Safety Index” (DSI) were obtained. Based upon a statistical analysis of the data we may conclude first that the effects of alcohol (approximately 0.10% BAC) vary widely from one subject to another (slighthly improved performance to highly impaired performance) and that the changes in the group averages of the means and standard deviations of the psychometric visual perception and risk acceptance functions, the driving skill distributions, the “Safety Distances” and the DSI's for the subjects (although all changes in the group averages are in the expected direction) are statistically not significant (α = .05). Second, the group average of the means of the choice reaction times for the subjects increased by 5% under the alcohol condition (statistically significant, α = .05), but more important the group average of the standard deviations of the choice reaction times for the subjects increased by 23% (statistically significant, α = .05). The group average of the information processing rates for the subjects decreased by 3% (statistically not significant, α = .05) under the alcohol condition. A system model in which the system demands on the driver are represented in terms of choice reaction times is used to demonstrate that the increase in performance variability (expressed by the standard deviation of choice reaction times) under the influence of alcohol provides a much better explanation for the higher accident involvement than the historically most frequently used rather small increase in average performance (expressed by the mean of choice reaction times).

scholarly journals Scale Invariant Contrasts of Response Latency Distributions

2018 ◽  
Author(s):  
Natarajan Sriram ◽  
Brian A. Nosek ◽  
Anthony G. Greenwald
Keyword(s):  
Individual Differences ◽  
Standard Deviation ◽  
Response Latency ◽  
Statistical Power ◽  
Scale Invariant ◽  
Scaling Effect ◽  
Latency Difference ◽  
The Mean ◽  
The Right ◽  
Latency Distributions

Individual differences in general speed lead to a positive correlation between the mean and standard deviation of mean latency. This “coarse” scaling effect causes the mean latency difference (MLD) to be spuriously correlated with general speed. Within individuals, the correlation between the mean and standard deviation of trial latencies leads contrasted distributions to increase their overlap as an MLD of fixed width is translated to the right. To address this “fine” scaling effect, contrasts based on within subject latency transformations including the logarithm, standardization, and ranking were evaluated and turned out to be distinctly superior to the MLD. Notably, the mean gaussian rank latency difference was internally consistent, eliminated fine scaling, meliorated coarse scaling, reduced correlations with general speed, increased statistical power to detect within subject and between group effects, and has the potential to increase the validity of inferences drawn from response latency data.

scholarly journals Internal consistency of the Regional Brewer Calibration Centre for Europe triad during the period 2005–2016

2018 ◽  
Vol 11 (7) ◽  
pp. 4059-4072 ◽  
Author(s):  
Sergio Fabián León-Luis ◽  
Alberto Redondas ◽  
Virgilio Carreño ◽  
Javier López-Solano ◽  
Alberto Berjón ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Data Sets ◽  
Individual Values ◽  
Relative Standard ◽  
The World ◽  
The Mean ◽  
The Individual ◽  
Ozone Column

Abstract. Total ozone column measurements can be made using Brewer spectrophotometers, which are calibrated periodically in intercomparison campaigns with respect to a reference instrument. In 2003, the Regional Brewer Calibration Centre for Europe (RBCC-E) was established at the Izaña Atmospheric Research Center (Canary Islands, Spain), and since 2011 the RBCC-E has transferred its calibration based on the Langley method using travelling standard(s) that are wholly and independently calibrated at Izaña. This work is focused on reporting the consistency of the measurements of the RBCC-E triad (Brewer instruments #157, #183 and #185) made at the Izaña Atmospheric Observatory during the period 2005–2016. In order to study the long-term precision of the RBCC-E triad, it must be taken into account that each Brewer takes a large number of measurements every day and, hence, it becomes necessary to calculate a representative value of all of them. This value was calculated from two different methods previously used to study the long-term behaviour of the world reference triad (Toronto triad) and Arosa triad. Applying their procedures to the data from the RBCC-E triad allows the comparison of the three instruments. In daily averages, applying the procedure used for the world reference triad, the RBCC-E triad presents a relative standard deviation equal to σ = 0.41 %, which is calculated as the mean of the individual values for each Brewer (σ157 = 0.362 %, σ183 = 0.453 % and σ185 = 0.428 %). Alternatively, using the procedure used to analyse the Arosa triad, the RBCC-E presents a relative standard deviation of about σ = 0.5 %. In monthly averages, the method used for the data from the world reference triad gives a relative standard deviation mean equal to σ = 0.3 % (σ157 = 0.33 %, σ183 = 0.34 % and σ185 = 0.23 %). However, the procedure of the Arosa triad gives monthly values of σ = 0.5 %. In this work, two ozone data sets are analysed: the first includes all the ozone measurements available, while the second only includes the simultaneous measurements of all three instruments. Furthermore, this paper also describes the Langley method used to determine the extraterrestrial constant (ETC) for the RBCC-E triad, the necessary first step toward accurate ozone calculation. Finally, the short-term or intraday consistency is also studied to identify the effect of the solar zenith angle on the precision of the RBCC-E triad.

Postnatal Development of a Left-Right Atrial Pressure Gradient

1956 ◽  
Vol 186 (3) ◽  
pp. 521-524 ◽  
Author(s):  
A. van Harreveld ◽  
F. E. Russell
Keyword(s):  
Left Ventricle ◽  
Pressure Gradient ◽  
Left Atrium ◽  
Postnatal Development ◽  
Right Atrial ◽  
Left And Right ◽  
The Mean ◽  
The Right ◽  
The Relationship ◽  
Equal Thickness

The mean left and right atrial pressures were measured in six groups of 10 kittens each. One group was examined between the 12th and 24th hour after birth, one group after 3 days, after 1 week, 2 weeks, 1 month and 2 months. The left and right atrial pressures were almost equal in the first group. With age an increasing left to right pressure gradient developed. In the oldest group the pressure in the left atrium was almost twice as great as in the right. Parallel with the pressure gradient a difference developed in the wall thicknesses of the left and right ventricles. At birth the ventricular walls were of about equal thickness; at age 2 months the left ventricle wall was more than twice as thick as the right. The relationship between ventricle wall thicknesses and atrial pressures is discussed.

Insight into neutron focusing: the out-of-focus condition

2013 ◽  
Vol 46 (5) ◽  
pp. 1361-1371 ◽  
Author(s):  
B. Hammouda ◽  
D. F. R. Mildner ◽  
A. Brûlet ◽  
S. Desert
Keyword(s):  
Standard Deviation ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Neutron Wavelength ◽  
Focus Condition ◽  
The Mean ◽  
The Individual ◽  
Multiple Holes ◽  
Good Agreement

Neutron focusing leads to significant gains in flux-on-sample in small-angle neutron scattering and very small angle neutron scattering instruments. Understanding the out-of-focus condition is necessary for less than optimal conditions such as for short instruments and low neutron wavelengths. Neutron focusing is investigated using a three-pronged approach. The three methods are analytical calculations, resolution measurements and computer simulations. A source aperture containing a single small-size hole and a sample aperture containing multiple holes are used to produce multiple spots on the high-resolution neutron detector. Lens focusing elongates off-axis spots in the radial direction. The standard deviation for the size of each spot is estimated using these three approaches. Varying parameters include the neutron wavelength, the number of focusing lenses and the location of holes on the sample aperture. Enough agreement for the standard deviation of the individual neutron beams was found between the calculations and the measurements to give confidence in this approach. Good agreement was found between the standard deviations obtained from calculations and simulations as well. Excellent agreement was found for the mean location of these individual spots.

Riders’ perception of symmetrical pressure on their ischial tuberosities and rein contact tension whilst sitting on a static object

2017 ◽  
Vol 13 (1) ◽  
pp. 7-12 ◽  
Author(s):  
R. Guire ◽  
H. Mathie ◽  
M. Fisher ◽  
D. Fisher
Keyword(s):  
Standard Deviation ◽  
Solid Wall ◽  
Static Model ◽  
Ischial Tuberosity ◽  
Static Object ◽  
Left And Right ◽  
And Performance ◽  
The Right ◽  
Ischial Tuberosities ◽  
Paired T Test

The horse-rider system is of great interest in understanding the mechanics involved in optimising locomotor function and performance in the ridden horse. Adult riders (n=30) attending a rider conference volunteered to take part in the study. Riders were asked to mimic riding position by positioning themselves symmetrically on their seat bones (ischial tuberosities) sitting on a (Pliance) pressure mat which was placed on a static platform. Riders were also asked to mimic even rein contact using reins with gauges which were attached to a solid wall. When satisfied that they were sitting symmetrically and had an even rein contact, pressure and rein measurements were captured for 5 s and repeated three times. A paired T Test was carried out to determine differences between left and right ischial tuberosities and rein pressures. Using a static model, this study found that the riders had significantly more pressure beneath the left ischial tuberosity (mean ± standard deviation, 3.22±1.43 N/cm2) compared to the right (2.65±1.49 N/cm2) (P=0.04) and no significant differences were observed between left (6.37±2.42 N) and right rein pressure (6.38±2.66 N) (P=0.95). Whilst sitting on a static platform, differences in ischial tuberosity pressure in adult riders were observed despite these riders’ perception that their seat was symmetrically weighted. These differences observed need to be investigated further, dynamically, to determine if there is a similar trend in the ridden situation.

A Proof for Rhiel's Range Estimator of the Coefficient of Variation for Skewed Distributions

2007 ◽  
Vol 100 (1) ◽  
pp. 208-210 ◽  
Author(s):  
G. Steven Rhiel
Keyword(s):  
Standard Deviation ◽  
Coefficient Of Variation ◽  
Research Study ◽  
Skewed Distributions ◽  
The Mean ◽  
Standard Deviations

In this research study is proof that the coefficient of variation ( CVhigh-low) calculated from the highest and lowest values in a set of data is applicable to specific skewed distributions with varying means and standard deviations. Earlier Rhiel provided values for dn, the standardized mean range, and an, an adjustment for bias in the range estimator of μ. These values are used in estimating the coefficient of variation from the range for skewed distributions. The dn and an values were specified for specific skewed distributions with a fixed mean and standard deviation. In this proof it is shown that the dn and an values are applicable for the specific skewed distributions when the mean and standard deviation can take on differing values. This will give the researcher confidence in using this statistic for skewed distributions regardless of the mean and standard deviation.

scholarly journals A New Method to Estimate the Systematical Biases of Expendable Bathythermograph

2011 ◽  
Vol 28 (2) ◽  
pp. 244-265 ◽  
Author(s):  
Lijing Cheng ◽  
Jiang Zhu ◽  
Franco Reseghetti ◽  
Qingping Liu
Keyword(s):  
Standard Deviation ◽  
Integral Method ◽  
Differential Method ◽  
Rate Coefficients ◽  
Temperature Error ◽  
Temperature Profiles ◽  
Fall Rate ◽  
Start Up ◽  
The Mean ◽  
The Individual

Abstract A new technique to estimate three major biases of XBT probes (improper fall rate, start-up transient, and pure temperature error) has been developed. Different from the well-known and standard “temperature error free” differential method, the new method analyses temperature profiles instead of vertical gradient temperature profiles. Consequently, it seems to be more noise resistant because it uses the integral property over the entire vertical profile instead of gradients. Its validity and robustness have been checked in two ways. In the first case, the new integral technique and the standard differential method have been applied to a set of simulated XBT profiles having a known fall-rate equation to which various combinations of pure temperature errors, random errors, and spikes have been added for the sake of this simulation. Results indicated that the single pure temperature error has little impact on the fall-rate coefficients for both methods, whereas with the added random error and spikes the simulation leads to better results with the new integral technique than with the standard differential method. In the second case, two sets of profiles from actual XBT versus CTD comparisons, collected near Barbados in 1990 and in the western Mediterranean (2003–04 and 2008–09), have been used. The individual fall-rate coefficients and start-up transient for each XBT profile, along with the overall pure temperature correction, have been calculated for the XBT profiles. To standardize procedures and to improve the terms of comparison, the individual start-up transient estimated by the integral method was also assigned and included in calculations with the differential method. The new integral method significantly reduces both the temperature difference between XBT and CTD profiles and the standard deviation. Finally, the validity of the mean fall-rate coefficients and the mean start-up transient, respectively, for DB and T7 probes as precalculated equations was verified. In this case, the temperature difference is reduced to less than 0.1°C for both datasets, and it randomly distributes around the null value. In addition, the standard deviation on depth values is largely reduced, and the maximum depth error computed with the datasets near Barbados is within 1.1% of its real value. Results also indicate that the integral method has a good performance mainly when applied to profiles in regions with either a very large temperature gradient, at the thermocline or a very small one, toward the bottom.

Alum Production from some Nigerian Kaolinite Deposits

2012 ◽  
Vol 7 ◽  
pp. 13-19 ◽  
Author(s):  
L.C. Edomwonyi-Otu ◽  
B.O. Aderemi ◽  
O. Edomwonyi-Otu ◽  
A. Simo ◽  
M. Maaza
Keyword(s):  
Standard Deviation ◽  
Surface Area ◽  
Science And Technology ◽  
Mineral Resources ◽  
Kaolinite Clay ◽  
Processing Technologies ◽  
Commercial Alumina ◽  
Bet Analysis ◽  
The Mean ◽  
Standard Deviations

The Development of Sustainable Processing Technologies for the Vast Mineral Resources Available in Nigeria and their Varied Applications Is a Major Pursuit by the Federal Ministry of Science and Technology. in this Work, Alum Was Produced from Three Different Kaolin Deposits in Nigeria Namely Kankara Brown, Bauchi and Kankara White by Acid Dealumination of the Metakaolin Obtained by Calcination of the Beneficiated Kaolinites and the Yields Were Measured to Ascertain the Process Repeatability. the Reproducibility Studies Carried Out on Samples from each Deposit Showed a Mean Yield of 80 %, 92 % and 87 % and Standard Deviation of 2.50 %, 1.063 % and 1.296 %, for Kankara Brown, Bauchi and Kankara White Respectively. the Values from the Three Deposits Fall within 3 Standard Deviations of the Mean in Accordance with the 68-95-99.7/three-Sigma Rule. the Alum Quality Also Compares Well with Available Commercial Alums in the Market. BET Analysis, of the Alumina Obtained by Calcination of the Alum (Kankara White), Gave a Surface Area of 192.2441m2/g Comparable to Commercial Alumina. these Results Suggest/establishes the Huge Possibility of Commercial Alum Production, Including Alumina, Using Kaolinite Clay from these Deposits as Starting Materials.

scholarly journals Growth-Related Differences in Maximum Laterotrusion and Retrusion between Children and Adults

2009 ◽  
Vol 79 (2) ◽  
pp. 265-270 ◽  
Author(s):  
Claudia A. Reicheneder ◽  
Peter Proff ◽  
Uwe Baumert ◽  
Tomas Gedrange
Keyword(s):  
Temporomandibular Joint ◽  
Null Hypothesis ◽  
Population Based ◽  
Adult Group ◽  
Population Based Study ◽  
Significant Difference ◽  
Left And Right ◽  
The Mean ◽  
The Right

Abstract Objective: To test the null hypothesis that there are no differences between children and adults in maximum laterotrusion and maximum retrusion on the right and left sides. Materials and Methods: This population-based study included 81 randomly selected children between the ages of 6 and 10 years and 67 adults. Kinematic variables were measured with the ultrasonic JMA-System for registration. Results: The mean maximum laterotrusion of the children's group (10.6 ± 1.5 mm on the left, 11.0 ± 1.7 mm on the right) was significantly smaller than that of the adult group (11.7 ± 2.0 mm on the left, 12.2 ± 1.7 mm on the right). The maximum laterotrusion of the children's group corresponded to about 90% on the left and right sides of that of the adult group. The mean maximum retrusion of the children's group was significantly bigger than that of the adult group. There, the adult values corresponded to 66.7% on the left and 50% on the right side of the children's values. No significant difference in maximum laterotrusion and retrusion was noted on the right and left sides, and no significant differences according to gender specificities were observed in either group. Conclusions: The hypothesis is rejected. In development of the temporomandibular joint, maximum laterotrusion on the right and left sides increases significantly with age, and maximum retrusion decreases significantly with age.

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