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Investigation 1- IB2. Random sampling and Quadrats (G.1.3). Population. A group of organisms of the same species living in the same area at the same time. Measuring Populations. It is usually impossible to count every member of a population
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Investigation 1- IB2 Random sampling and Quadrats (G.1.3)
Population • A group of organisms of the same species living in the same area at the same time
Measuring Populations • It is usually impossible to count every member of a population • Ecologists often use methods to estimate the population size
Random Sampling • A sample, or part of an area, is chosen to illustrate what the whole population is like • In a random sample, every individual has an equal chance of being selected • Small numbers of individuals, in randomly located parts of the total area, are counted • This method is suitable for organisms that do not move around!
Random Sampling – Quadrats • Square sample areas of equal size, marked out by a frame • Useful when study area is uniform • When study area is sloped or irregularly shaped, quadrat can be used together with a line transect (which we did in grade 10)
Our study is in the quad… analyzing red clover and dandelion population sizes..
Random sample generating using your TI-83 • Stat • Edit • L1 Highlighted • Green / + sign • MATH • PRB • 5- Random Integer • (1,5,10) L1 • (1, 10, 10) L2 • Green • + • Enter • * Do the same for L2 to get your co-ordinates.
Calculating population • Population size= mean number per quadrat * total area / area of each quadrat • Page 152 leaf book
After the population size has been determined of each you can conclude whether you or not you think pesticides are used or not on the school grounds… • How can we be sure?