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What are error bars for?
They are a graphical representation of the variability of the data
What is standard deviation for?
Summarize the spread of values around the mean. 68% of the values fall within one SD of the mean.
How much data falls within 2 SD of the mean?
What does a small standard deviation mean?
Data is clustered around the mean value.
What does a large standard deviation mean?
There is a wider spread around the mean.
What does the t-test do?
- It uses the standard deviations of both sets of data to deduce the significance of the difference.
- It helps scientists work out if the difference is significant or not.
What are the 'degrees of freedom' if you have 2 samples, both with a population of 10?
- Degrees of freedom are the sum of the samples ize of each of the two groups minus 2.
- For example, if two groups of 10 plants each are being looked at, then 10 plus 10 is 20 minus 2 is 18. Thus, the number to look at in the ‘Degrees of freedom’ column is 18.