# Distribution of Organisms

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• Created by: I
• Created on: 05-04-14 15:20

## How to use Quadrat to study distribution

• Place a 1m squared quadrat onto the ground at a random point wthin the first sample area. Divide the area into a grid and use a random number generator to pick the coordinates
• Count all the organisms within the quadrat.
• repeat steps above as many times as you can.
• Work out the mean number of organisms within the first sampl area
• Repeat steps 1-4 in the second sample area
• Finally compare the two means

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## How to use a transect

• Mark out a line in the area you want to study using a tape measure
• Collect data along the line
• Do this by just counting all the organisms youre interested in that touch the line
• Or collect data by using quadrats. Theses can be placed next to each other along th line or at intervasl for exapmle every 2m
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## Reliability & Validility

Make sure results are repeatable and reproducible

To make results more reliable:

• Take a large sample size. Bigger samples are more representative of the whole population
• use random samples randomly put down ormark out your quadrat/transect If all samles are in one spot and everywhere is different the results won't be reproducible

Validity

Must be reliabe and anser original question- need to control all the vriables.

Contol variables => know whether there is a difference in distribuion is caused by an environmental factor or not

Dont control variables=> wont know if a correlation has bee found because of chance the environmental factor  or because of a different variable- study will not give valid data

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