To ensure that your results are valid, consider the following guidelines when you collect data, perform the analysis, and interpret your results.
You must have continuous data, such as the weights of packages, or discrete data, such as the number of complaints.
In statistics, random samples are used to make generalizations, or inferences, about a population. If your data are not collected randomly, your results may not represent the population. For more information, go to Randomness in samples of data.
For observations to be independent, the value of a particular observation does not depend on any previous observation. If your observations are not independent, your results may not be valid. For more information, go to How are dependent and independent samples different?.
If your sample size is small, the resampling results may be unreliable. To ensure that your results are valid, collect a medium to large sample. An adequate sample size depends on the characteristics of the data. Use the histogram to determine whether your sample size is large enough.