Which statistical method is used for checking the reliability of a sample?

The statistical method used for checking the reliability of a sample is test-retest reliability. This approach assesses the consistency of a measure over time. Essentially, it involves measuring the same group of subjects at two different points in time using the same measurement instrument. If the results show high correlation, it indicates that the instrument is reliable and produces stable results over time.

Test-retest reliability is particularly important when dealing with psychological tests, surveys, or any other kind of measurement where consistency is critical. This method helps to ascertain that fluctuations in data are more related to actual changes in the measured phenomenon rather than inconsistencies in the measurement process itself.

In contrast, regression analysis is typically used to identify relationships between variables rather than to assess an instrument's reliability. Sampling error analysis focuses on the error associated with using a sample to estimate population parameters, and variance analysis is used to examine differences among group means in a sample rather than measuring reliability directly. Therefore, test-retest reliability is the most appropriate method for checking the consistency of a measurement instrument over time.