Maths

Question 1

When should the chi-squared test be used?

Answer 1

• Frequencies
• Collecting data about the number of individuals in particular categories
• Eg. Genetic cross experiments, choice chamber behavioural studies or count number of individuals of different species.

Question 2

How do you do the chi-squared test?

Answer 2

1. Degrees of freedom = number of categories - 1
2. Compare calculated and critical at the value of 0.5 significance
3. Calculated is greater than critical then reject the hypothesis as a significant difference not due to chance.

Question 3

When should you use the student T-Test?

Answer 3

• Collecting data that are measurements
• Looking for differences between measurements of the same variable from different samples
• Eg. two different environments same DV but different IV.

Question 4

How do you use the student T-Test?

Answer 4

• Degrees of freedom = number in sample 1 + number in sample 2 - no. of samples.
• Compare the calculated value of T and critical value at p=0.05
• If calculated is greater or equal to critical then reject the null hypothesis - less than 5% probability that the difference between mean values are due to chance

Question 5

When should I use the Spearman Rank test?

Answer 5

• Collecting data that are measurements
• Looking for a correlation between measurements of the different variable from the sample.
• Eg. leaf length and leaf width correlation or nitrogen conc and length of invertebrate.

Question 6

When should the index of diversity be used?

Answer 6

• Will be told to use!!
• Investigate the species richness in a community

Question 7

What is normal distribution?

Answer 7

Bell shaped curve of continuous variation eg. height or weight

Question 8

What is the mean?

Answer 8

max height of normal distribution curve

Question 9

What is standard deviation?

Answer 9

distance from mean when curve change from being convex to concave - gives measure of range of value on either side of mean.