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  2. Estimation of covariance matrices - Wikipedia

    en.wikipedia.org/wiki/Estimation_of_covariance...

    Estimation of covariance matrices then deals with the question of how to approximate the actual covariance matrix on the basis of a sample from the multivariate distribution. Simple cases, where observations are complete, can be dealt with by using the sample covariance matrix .

  3. Questionnaire construction - Wikipedia

    en.wikipedia.org/wiki/Questionnaire_construction

    The following types of reliability and validity should be established for a multi-item scale: internal reliability, test-retest reliability (if the variable is expected to be stable over time), content validity, construct validity, and criterion validity. Factor analysis is used in the scale development process.

  4. Kendall rank correlation coefficient - Wikipedia

    en.wikipedia.org/wiki/Kendall_rank_correlation...

    The denominator is the total number of pair combinations, so the coefficient must be in the range −1 ≤ τ ≤ 1.. If the agreement between the two rankings is perfect (i.e., the two rankings are the same) the coefficient has value 1.

  5. Data analysis - Wikipedia

    en.wikipedia.org/wiki/Data_analysis

    The data is necessary as inputs to the analysis, which is specified based upon the requirements of those directing the analytics (or customers, who will use the finished product of the analysis). [ 14 ] [ 15 ] The general type of entity upon which the data will be collected is referred to as an experimental unit (e.g., a person or population of ...

  6. Process tracing - Wikipedia

    en.wikipedia.org/wiki/Process_tracing

    Process tracing is a qualitative research method used to develop and test theories. [1] [2] [3] Process-tracing can be defined as the following: it is the systematic examination of diagnostic evidence selected and analyzed in light of research questions and hypotheses posed by the investigator (Collier, 2011).

  7. Quality assurance - Wikipedia

    en.wikipedia.org/wiki/Quality_assurance

    Quality assurance (QA) is the term used in both manufacturing and service industries to describe the systematic efforts taken to assure that the product(s) delivered to customer(s) meet with the contractual and other agreed upon performance, design, reliability, and maintainability expectations of that customer. The core purpose of Quality ...

  8. Software testing - Wikipedia

    en.wikipedia.org/wiki/Software_testing

    The sample below is common for waterfall development. The same activities are commonly found in other development models, but might be described differently. Requirements analysis: testing should begin in the requirements phase of the software development life cycle. During the design phase, testers work to determine what aspects of a design ...

  9. Big data - Wikipedia

    en.wikipedia.org/wiki/Big_data

    The truthfulness or reliability of the data, which refers to the data quality and the data value. [37] Big data must not only be large in size, but also must be reliable in order to achieve value in the analysis of it. The data quality of captured data can vary greatly, affecting an accurate analysis. [38] Value