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Related Concept Videos

Coefficient of Variation01:10

Coefficient of Variation

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The coefficient of variation measures the dispersion of the data points or distribution around the mean. Using the coefficient of variation, we can compare two data series with drastically different means or different units of measurement. The coefficient of variation for a sample and a population is expressed as a percentage of the ratio of standard deviation to the mean.
The coefficient of variation is a practical statistical tool in finance. It allows investors to assess the volatility or...
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Coefficient of Correlation01:12

Coefficient of Correlation

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The correlation coefficient, r, developed by Karl Pearson in the early 1900s, is numerical and provides a measure of strength and direction of the linear association between the independent variable x and the dependent variable y.
If you suspect a linear relationship between x and y, then r can measure how strong the linear relationship is.
What the VALUE of r tells us:
The value of r is always between –1 and +1: –1 ≤ r ≤ 1.
The size of the correlation r indicates the...
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Confidence Coefficient01:24

Confidence Coefficient

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The confidence coefficient is also known as the confidence level or degree of confidence. It is the percent expression for the probability, 1-α, that the confidence interval contains the true population parameter assuming that the confidence interval is obtained after sufficient unbiased sampling; for example, if the CL = 90%, then in 90 out of 100 samples the interval estimate will enclose the true population parameter. Here α is the area under the curve, distributed equally under...
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Thermodynamics: Activity Coefficient01:24

Thermodynamics: Activity Coefficient

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Activity is the measure of the effective concentration of the species in solution. It can be expressed as the product of the molar concentration of the species and its activity coefficient. The activity coefficient is a dimensionless quantity and depends on the total ionic strength of the solution.
The activity coefficient is a measure of the deviation from ideal behavior. When the ionic strength of the solution is minimal, the activity coefficient of an ionic species is close to unity, making...
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Factors Affecting Activity Coefficient01:17

Factors Affecting Activity Coefficient

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The extended Debye-Hückel equation indicates that the activity coefficient of an ion in an aqueous solution at 25°C depends on three partially interdependent properties: the ionic strength of the solution, the charge of the ion, and the ion size. 
The activity coefficient value for an ion is close to one when the solution has almost zero ionic strength, i.e., when the solution shows close to ideal behavior. As the ionic strength of the solution increases from 0 to 0.1 mol/L, a...
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Kendall's Coefficient of Concordance01:20

Kendall's Coefficient of Concordance

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Kendall's Coefficient of Concordance (W), also known as Kendall's W, is a non-parametric statistical measure used to assess the agreement or concordance between multiple raters or judges when they rank a set of items. It is often used when you have ordinal data (ranks) and you want to see if there is consistency or consensus among the raters. It is widely applied in research areas such as psychology, medicine, and social sciences, where multiple judges are asked to rank or rate subjects...
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Determination of the Friction Coefficients of Icy Pavements Under Different Amounts of Snowfall
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Thanks Coefficient Alpha, We Still Need You!

Tenko Raykov1, George A Marcoulides2

  • 1Michigan State University, East Lansing, MI, USA.

Educational and Psychological Measurement
|January 15, 2019
PubMed
Summary
This summary is machine-generated.

Coefficient alpha remains a dependable reliability estimator for multi-component instruments when specific conditions are met. Recent critiques overlook decades of research supporting its empirical utility and relevance.

Keywords:
coefficient alphameasuring instrumentpopulation discrepancyreliabilitysingle-factor model

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Area of Science:

  • Psychometrics
  • Measurement Theory
  • Statistical Reliability

Background:

  • Coefficient alpha is a widely used metric for assessing the internal consistency of multi-component measuring instruments.
  • Recent literature has raised criticisms questioning the utility and applicability of coefficient alpha.
  • These critiques often neglect substantial historical research demonstrating coefficient alpha's empirical relevance.

Purpose of the Study:

  • To re-evaluate the merits and conditions of using coefficient alpha.
  • To address oversights in recent critical publications regarding coefficient alpha.
  • To reaffirm the value of coefficient alpha as a reliability estimator.

Main Methods:

  • Review of historical and contemporary psychometric literature.
  • Analysis of empirical research on coefficient alpha's utility.
  • Examination of the conditions under which coefficient alpha is a valid reliability estimator.

Main Results:

  • Decades of research confirm the empirical relevance and utility of coefficient alpha.
  • Coefficient alpha is a dependable reliability estimator when its underlying assumptions are met.
  • Specific empirical circumstances validate the use of coefficient alpha.

Conclusions:

  • Coefficient alpha should be retained as a valuable tool for assessing measurement reliability.
  • Abandoning coefficient alpha would disregard significant empirical findings.
  • Adherence to the conditions for its use ensures the dependability of coefficient alpha as a reliability estimator.