10.5 quantative investigations of variations

what is inter-specific variation?

* one species differing from another

what is intraspecfic variation?

members of the same species differing

In what ways may a sample collected be unrepresentative? (2)

* sampling bias - unrepresentative due to the selection process
* chance - unrepresentative due to chance

how do we get rid of sampling bias?

random sampling

how to carry random sampling?

1)divide the study area into a grid of numbers lins

2)using random numbers from a table or gerneated by a computer (obtain a sereis of coordinates)

3)take samples at the intersection of each pair of coordinates

How do we minimize the effect of chance from the sampling process?

* using a large sample size -

lessens the influence of anomalies

* analysis of the data collected

\- statistical tests to determine how much of the results was influenced by chance

10\.5 - Quantitative investigations of variation within a species involve:

* collecting data from random samples
* calculating a mean value of the collected data
* calculating standard deviation of that mean interpreting mean values + their standard deviations

What is required for studying variation?

The population must be sampled

How is a sample ensured not to be biased?

The sample should be random

Why is the standard deviation of a sample useful?

* Standard deviation gives an indication of variation
* A large standard deviation means large variation
* A small standard deviation means small variation

How can standard deviation be seen visually?

* Using error bars .
* The longer the error bar, the higher that standard deviation and the greater the variation

what does a normal standard deviation curve?

mean median mode

* mean,median and mode all have same value.

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what is the calculation for standard deviation?

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what is the mean ?

what is standard deviation?

a measure of the spread of values about the mean.

* this only works for continuous data