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Data checking

After having entered the data, you should carefully check the data to ensure that they have been entered correctly.

Sometimes erroneous data input will become apparent when looking at the data range in the summary statistics report (e.g. maximum value of 78 for pH), or when plotting box-and-whisker plots, dot plots or scatter diagrams for the different variables. You should check clear outliers since they may indicate incorrect data entry, or they may result from a technical failure in measurement or from a study protocol violation. Only for such plausible reason you may exclude a value from further analysis, and not simply because a value is the smallest or largest. If there is no evidence of such a mistake then the value must remain unaltered.

You can locate any value in the spreadsheet using the Find procedure.

You can exclude outliers from further calculations by using the Exclude command.

See also