Sampling prac

• Why do we take samples to estimate population size?

  To save time and reduce counting errors
• What is the golden rule for sampling to represent a population?

  Use random sampling to avoid bias
• What is considered a large sample size according to AQA?

  Over 30
• What type of sampling is used for uneven distribution?

  Line transect sampling
• How does random sampling differ from systematic sampling?

  Random sampling avoids bias, systematic does not
• What is the size of a typical quadrat used in sampling?

  50 cm by 50 cm
• What is the first step in random sampling using a quadrat?

  Take measures at a right angle
• How do you generate coordinates for random sampling?

  Use a random number generator
• What data collection methods can be used in random sampling?

  Density, percentage cover, local frequency
• Why is it important to repeat sampling at least 30 times?

  To ensure accurate representation of the population
• What is a line transect used for?

  To sample unevenly distributed organisms
• What is an interrupted belt transect?

  Quadrats placed at intervals along a line
• What is the advantage of using a belt transect?

  It samples different sections effectively
• How does local frequency differ from density in sampling?

  Local frequency counts presence in squares
• How do you calculate the estimated population size using density?

  Count individuals in quadrat, scale up
• What is the formula to estimate population size from density?

  Field size divided by quadrat size
• What is percentage cover in sampling?

  Estimation of full squares covered by species
• What are the pros of using local frequency?

  Quick and useful for large areas
• What are the cons of using density for sampling?

  Time-consuming and requires clear identification
• Why is percentage cover considered subjective?

  It relies on personal estimation of coverage
• What limitations does percentage cover have in sampling?

  Doesn't account for overlapping plants' sizes
• What is the significance of using a quadrat for sampling?

  It helps in estimating plant populations accurately
• How does environmental factors affect species distribution?

  They influence where species can thrive
• Why is it important to visualize plant coverage for percentage cover estimation?

  To improve accuracy in estimating coverage