Investigating Diversity

Question 1

Describe how we could carry out random sampling of a population

Answer 1

Divide area into a grid, generate random numbers (e.g. using random number generator) to create co-ordinates. Sample (e.g. using a quadrat) from these co-ordinates. Take several samples in order to calculate a mean

Question 2

What is standard deviation?

Answer 2

Standard deviation is a measure of the range of values either side of the mean. It gives us an indication of the “spread” of data.

Question 3

How do we calculate the mean?

Answer 3

Add all the numbers up, divide by the number of numbers

Question 4

What is the mode?

Answer 4

The single value of a sample which occurs the most often

Question 5

How do we find the median?

Answer 5

Arrange the values in ascending order, and identify the central/middle value.

Question 6

Why may standard deviation be a better measure of dispersion than the range?

Answer 6

Standard deviation takes into account all values and is less likely to be affected by extreme outliers.

Question 7

What is sampling bias?

Answer 7

Sampling bias is where the investigators make choices that mean their data is unrepresentative of the population

Question 8

How can we reduce the impact of sampling bias?

Answer 8

Select random areas to sample (e.g. using random coordinates produced by a random number generator)

Question 9

How can we reduce the impact of chance on random sampling?

Answer 9

Take a larger sample size, the larger the sample size the more likely the results are to be representative of the population and the less likely the results are due to chance. Additionally, use statistical tests to determine the likelihood that chance influenced the results.