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Using statistics in biology (data analysis): Mean, median, mode, standard deviation, standard error of mean, error bars
Data within one standard of the mean represents ~68% of your dataset. Two standard deviations is 97% within your data
$ What is standard error?
standard error = standard deviation/sqrt(# of samples)
How close your mean is to the actual mean.
If the error bars overlap, that means that we are not confident enough that the values are different to onsider “statistically significant”.
Distribution of data
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xs-s,s-m,m-l,l-xl
x-axis
Measurement over time.
The x-axis is always time
Time is constant, not an independent variable in a line graph
$ Is the x-axis an independent variable (in line graphs)?
No, the x-axis is a control variable, time.
Data is in percentages, out of 100%
Comparing averages
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x-axis is non-numerical
R^2
$ What is R^2 (scatter plot)?
The R^2 value denotes how much of the variance in your dependent variable is explained by your independent variable. An R^2 value of 1 means 100% of the variance is explained. A high R^2 value indicates a high likelhood that two variables are correlated.
Examples:
Figure 4. Relationship between female stickleback standard length in millimeters and the number of eggs per clutch. The length of a female stickleback correlates well with total number of eggs she will product.