Aquascope Facts

Mixing control areas with experimental areas

Mixing several control areas with several experimental areas solves this problem because we will be able to calculate the average number for both species of mussel that exist in the experimental areas compared to the control areas.
    If variations between the areas are caused only by natural variations that always occur along beaches, then there is no reason for the averages to be different. When the experimental and control areas are chosen randomly, there should not be a larger supply of food only to the experimental area from natural causes. Since we have a mixture of experimental and control areas, every set of areas (experimental and control), should on average be equal because all of them have been exposed to the same natural variation.
    If on the contrary it is as prescribed in the hypothesis, we expect on average an increase in the number of mussels within the experimental areas after competitors have been removed, independent of natural variations between the different places. To be able to make a proper comparison of these averages we must have several control and experimental areas.

Statistical analysis

This leads to additional complications. We now have the averages and variations between the different experimental and control areas, which we have to manage. Therefore, we must statistically analyse our findings. When we decide if competition has had any effect, it is not enough to guess if the averages are different enough in relation to the variation. we need to analyze our findings with a statistical test. We do not describe here how a statistical analysis is conducted, but to be able to conduct the statistical test and to base a support of the hypothesis on falsification, we must change the hypothesis to what is known as the null hypothesis.
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Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson