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Unformatted text preview: you measured) 3. Label both axes and
include units Graph Details
4. Use easy to read and even
increments on both axes
5. Plot the points (use
EXCEL)
6. Do NOT “connect the
dots”
 use a ‘bestfit’ or ‘trendline’ Graph Details
7. Use real graph paper: Fit figure on paper Fig 1. Growth of oaks over time Data Analysis
Descriptive Statistics
* Describe the population of data points collected
Population vs. Sample: A sample is a small subset representative of a
population
Mean: Average of a series of data points
Standard Deviation: This value shows you how far from the mean the
data spreads.
* Uses the same units as the mean
* Represented as Mean ± StDev n ∑( x * Use standard deviation to plot error bars:
StDev = i − x) i−1 n −1 Data Analysis
Once you have calculated descriptive statistics
(mean and standard deviation) you can use these
values to determine which of your hypotheses
should be rejected Evaluate how similar the results of two treatments
really are Using descriptive statistics: Standard deviation
+ 2.1 from the mean
 2.1 from the mean
StDev = 2.1 Average Number of fruits produced 1. Plot the mean and standard deviation for you data
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Not fertilized Fertilized Using descriptive statistics: Average Number of fruits produced 2. Determine the amount of overlap between the error
bars of the control and treatment
Do the error bars overlap? 20
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Is there a statistically
significant difference
between the number of
fruits produced in the
treatment (fertilized
soil) and control
(unfertilized soil)?
NO!!
Not fertilized Fertilized Using descriptive statistics:
2b. Determine the amount of overlap between these treatments
Do the error bars overlap
between Maple and Oak?
 NO
Is there a statistical
difference in the growth
rate of Maple and Oak?
YES!!!!
What about...
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This note was uploaded on 03/23/2014 for the course BIOL 1005 taught by Professor Ta during the Spring '07 term at LSU.
 Spring '07
 TA

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