Investigating Variation

• What is variation?

  The differences that exist between individuals
• What are the causes of variation?

  • Genetic factors - (different species have different genes causing variation between species. Individuals of the same species have the same genes but different alleles)
  • Differences in environments (climate, food)
  • Or a combination of genetics and environmental factors
• When studying variation within a species what sample side do you use?

  We use a Population

  It would be too time consuming and difficult to catch all the individuals in a group
• What type of sampling is used?

  Random sampling
• Why is random sampling used?

  • To make sure it is not biased
  • Needs to accurately represent the whole population
• What is the formula for calculating a mean

  total of all the values in data

  mean= ---------------------------

  the number of values in data
• What is a normal distribution?

  There are values on both sides of the mean

  Bell shaped curve on the graph
• Formula for standard deviation