A measure of spread showing how far values typically lie from the mean.
SD measures spread around the mean; roughly 68 percent of values fall within one SD in a normal distribution. Sample SD uses n-1. A low SD suggests data are clustered.
Large SD means data are widely spread. Use the same units as the data. In normal data about 95 percent lie within two SD.
Key idea: SD describes variation in the sample; SE describes the precision of the mean.
A measure of spread showing how far values typically lie from the mean.
Standard Deviation is one of the 51 topics in Lab Methods & Biostatistics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include t-Test, Standard Error and Error Bars, Reliability and Validity.
Comparing variability of heights between two groups.
Work through the Beginner topics in Lab Methods & Biostatistics first, such as Scientific Method, Hypothesis, Variables, then return to Standard Deviation. Intermediate topics assume the Beginner vocabulary.
The closest topics to Standard Deviation are t-Test, Standard Error and Error Bars, Reliability and Validity, Mean, Median and Mode. Comparing them side by side is a good way to see how the ideas connect.
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Standard Deviation. To practise the whole of Lab Methods & Biostatistics, use the Lab Methods & Biostatistics quiz.
Standard Deviation: A measure of spread showing how far values typically lie from the mean. t-Test: A test for significant differences between the means of two groups. Read both side by side and note what each one explains.
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with t-Test and explain the difference aloud. Finally, take the Lab Methods & Biostatistics quiz and come back to this page for any question you miss.
A test for significant differences between the means of two groups.
📊 Lab Methods & BiostatisticsThe standard error reflects the precision of a mean and is often displayed as error bars.
📊 Lab Methods & BiostatisticsReliable results are repeatable; valid results measure what they claim to measure.
📊 Lab Methods & BiostatisticsMeasures of central tendency summarising a data set.
📊 Lab Methods & Biostatistics