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level: 10.5 Quantitative investigations of variation

Questions and Answers List

level questions: 10.5 Quantitative investigations of variation

QuestionAnswer
Interspecific variation- If 1 species differs from another
Variation- Differences between individuals - Can be caused by genetic or environmental factors or a combination
Intraspecific variation- Members of the same species differing from each other
What influences results- Sampling bias - Chance - Large sample size - Analysis of the data collected
Sampling bias- Selection may be biased - The investigators may be making unrepresented choices either deliberately or unwittingly
Best way to prevent sampling bias- Random sampling
Random sampling method- Mark up a grid on a map of the study area - Label the grid with coordinates - Use a random number generator to choose a set of coordinates
Chance- Even if sampling bias is avoided, individuals chosen may, by pure chance, not be representative
Using large sample size- The more individuals that are selected the smaller the probability that chance will influence the result - So the less influence anomalies will have
Analysis of the data collected- Accepting that chance will play a part, the data can be analysed using statistical tests - To see how much chance may have influenced the data or any other cause
Standard deviation- A measure of the width of the curve - Shows us the spread of data around the mean
Calculating standard deviationSD = √Σ (x - X̄)²/n-1 Σ = sum of x = measured value (from sample) X̄ = mean value n = total no. of values in the sample