* Cronbach's alpha

The most common internal consistency measure is Cronbach's alpha, which is usually interpreted as the mean of all possible split-half coefficients.

Cronbach's alpha is a generalization of an earlier form of estimating internal consistency, Kuder – Richardson Formula 20.

Although the most commonly used, there are some misconceptions regarding Cronbach's alpha

In statistics, Cronbach's ( alpha ) is a coefficient of reliability.

This article discusses the use of in psychology, but Cronbach's alpha statistic is widely used in the social sciences, business, nursing, and other disciplines.

The standardized Cronbach's alpha can be defined as

Cronbach's alpha will generally increase as the intercorrelations among test items increase, and is thus known as an internal consistency estimate of reliability of test scores.

Because intercorrelations among test items are maximized when all items measure the same construct, Cronbach's alpha is widely believed to indirectly indicate the degree to which a set of items measures a single unidimensional latent construct.

A commonly accepted rule of thumb for describing internal consistency using Cronbach's alpha is as follows, however, a greater number of items in the test can artificially inflate the value of alpha and so this rule of thumb should be used with caution:

Then Cronbach's alpha equals

Another similarity is that while IRT provides for a standard error of each estimate and an information function, it is also possible to obtain an index for a test as a whole which is directly analogous to Cronbach's alpha, called the separation index.

The separation index is typically very close in value to Cronbach's alpha.

Internal consistency is usually measured with Cronbach's alpha, a statistic calculated from the pairwise correlations between items.

A small ( 133 student-subject ) validation study indicated that the scale had good internal reliability ( a Cronbach's alpha of 0. 85 ).

# redirect Cronbach's alpha

where is the separation index of the set of estimates of, which is analogous to Cronbach's alpha ; this is, in terms of Classical test theory, is analogous to a reliability coefficient.

The internal consistency for the BDI-IA was good, with a Cronbach's alpha coefficient of around 0. 85, meaning that the items on the inventory are highly correlated with each other.

During this analysis, one inspects the variances of the items and the scales, the Cronbach's α of the scales, and the change in the Cronbach's alpha when an item would be deleted from a scale.

Calculation of Cronbach's is included in many standard statistical packages such as SPSS and SAS.

However, IRT is not included in standard statistical packages like SPSS and SAS, whereas these packages routinely provide estimates of Cronbach's.

However, general statistical packages often do not provide a complete classical analysis ( Cronbach's is only one of many important statistics ), and in many cases, specialized software for classical analysis is also necessary.

A commonly used measure is Cronbach's α, which is equivalent to the mean of all possible split-half coefficients.

Instead, researchers use a measure of internal consistency known as Cronbach's.

Perhaps the most commonly used index of reliability is Cronbach's α, which is equivalent to the mean of all possible split-half coefficients.

Cronbach's can be shown to provide a lower bound for reliability under rather mild assumptions.

Thus, the reliability of test scores in a population is always higher than the value of Cronbach's in that population.

In contrast to Niels Bohr, who proposed a statistical version of the conservation laws to explain the phenomenon, Pauli hypothesized an undetected particle that he called a " neutron " in keeping with convention employed for naming both the proton and the electron, which in 1930 were known to be respective products for alpha and beta decay.

The heavy aluminium tri-alkyls are reacted with ethylene again in a displacement or a tranalkylation reaction, but at high temperature ( over 400 ° F ) and at low pressure ( less than 1000 psig ) to recover triethyl aluminium and a statistical distribution of linear alpha olefins, which serve as the olefin diluent in the chain-growth step.

* The Lyman alpha forest, which allows cosmologists to measure the distribution of neutral atomic hydrogen gas in the early universe, by measuring the absorption of light from distant quasars by the gas.

For example, alpha, the widely used measure of test reliability was developed by educational psychologist Lee Cronbach.

The reaction was repeated in 1994 and the team were able to measure both alpha decay and spontaneous fission for < sup > 264 </ sup > Hs.

Common measures are the Sharpe ratio., Treynor measure and Jensen's alpha.

* A cosmic ray telescope, mounted inside the body pointing in anti-solar direction, to measure the direction and energy spectrum of protons and alpha particles.

Ionizing radiation, such as X-rays, alpha rays, beta rays, and gamma rays, are undetectable by the human senses, therefore a measuring device is used to detect, measure and record this, and in some cases give an alarm when a preset level is exceeded.

The biological half-lives " alpha half-life " and " beta half-life " of a substance measure how quickly a substance is distributed and eliminated.

As a result, alpha is most appropriately used when the items measure different substantive areas within a single construct.

A key feature is its ability to measure the energy of incident radiation, and it is widely used where discrimination between radiation types is required, such as between alpha and beta particles.

Jensen's alpha was first used as a measure in the evaluation of mutual fund managers by Michael Jensen in 1968.

Generalizing the above definition to the multifactor setting, Jensen's alpha is a measure of the marginal return associated with an additional strategy that is not explained by existing factors.

Varying coefficient meta-analysis methods for alpha reliability, Psychological Methods, 15, 368 – 385.

As an engineer, May is most noted for having solved the " alpha particle problem ", which was affecting the reliability of integrated circuits as device features reached a critical size where a single alpha particle could change the state of a stored value and cause a single event upset.

The RWA scale also has excellent internal reliability, with coefficient alpha typically measuring between 0. 85 and 0. 94.