# AS Biology

• Created by: Lois
• Created on: 26-05-15 12:17
Problems with sampling
Difficult to sample the whole population as too time consuming and impossible with mobile species
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Why sample?
make a representation of the whole society
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How to prevent bias?
Use a random number generator in order to generator number co-ordinates. Divide the area into a grid
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How to ensure variation is not due to chance?
It is important to analyse the results statisitcally. Large sample size
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What is standard deviation?
It is the variation around the mean, tells us how much a single sample varies
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How do you measure SD?
The width of the curve. The range of values around the mean. Point of inflection
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What is mean?
It is the average of the values collected in the sample. Useful when comparing one to another
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SD?
SQUARE ROOT OF sum of (x-mean)2/ n
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## Other cards in this set

### Card 2

Why sample?

#### Back

make a representation of the whole society

### Card 3

#### Front

How to prevent bias?

### Card 4

#### Front

How to ensure variation is not due to chance?

### Card 5

#### Front

What is standard deviation?