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  2. Research - Wikipedia

    en.wikipedia.org/wiki/Research

    Determining specific research ... theory or being able to estimate the size of a phenomenon of interest. ... 70% of articles in a random sample of publications about ...

  3. Cluster sampling - Wikipedia

    en.wikipedia.org/wiki/Cluster_sampling

    An example of cluster sampling is area sampling or geographical cluster sampling.Each cluster is a geographical area in an area sampling frame.Because a geographically dispersed population can be expensive to survey, greater economy than simple random sampling can be achieved by grouping several respondents within a local area into a cluster.

  4. Normality test - Wikipedia

    en.wikipedia.org/wiki/Normality_test

    Simple back-of-the-envelope test takes the sample maximum and minimum and computes their z-score, or more properly t-statistic (number of sample standard deviations that a sample is above or below the sample mean), and compares it to the 68–95–99.7 rule: if one has a 3σ event (properly, a 3s event) and substantially fewer than 300 samples, or a 4s event and substantially fewer than 15,000 ...

  5. Confidence interval - Wikipedia

    en.wikipedia.org/wiki/Confidence_interval

    Factors affecting the width of the CI include the sample size, the variability in the sample, and the confidence level. [4] All else being the same, a larger sample produces a narrower confidence interval, greater variability in the sample produces a wider confidence interval, and a higher confidence level produces a wider confidence interval. [5]

  6. Z-test - Wikipedia

    en.wikipedia.org/wiki/Z-test

    Difference between Z-test and t-test: Z-test is used when sample size is large (n>50), or the population variance is known. t-test is used when sample size is small (n<50) and population variance is unknown. There is no universal constant at which the sample size is generally considered large enough to justify use of the plug-in test.

  7. Replication (statistics) - Wikipedia

    en.wikipedia.org/wiki/Replication_(statistics)

    In engineering, science, and statistics, replication is the process of repeating a study or experiment under the same or similar conditions to support the original claim, which crucial to confirm the accuracy of results as well as for identifying and correcting the flaws in the original experiment. [1]

  8. G*Power - Wikipedia

    en.wikipedia.org/wiki/G*Power

    G*Power has a built-in tool for determining effect size if it cannot be estimated from prior literature or is not easily calculable. ... sample size, and effect size ...

  9. Wald test - Wikipedia

    en.wikipedia.org/wiki/Wald_test

    Let ^ be our sample estimator of P parameters (i.e., ^ is a vector), which is supposed to follow asymptotically a normal distribution with covariance matrix V, (^) (,). The test of Q hypotheses on the P parameters is expressed with a Q × P {\displaystyle Q\times P} matrix R :