counting populations estimations & random samples
TRANSCRIPT
What are the 3 biggest populations in this pond community?
Name of Population
Ducks Cattails Water Lilies
Actual Count
Sample Count
ACTUAL COUNT
• Each member of a population is counted one by one
Name of Population
Ducks Cattails Water Lilies
Actual Count
6 20 4
Sample Count
RANDOM SAMPLES•Make a GRID
•Count the total number of squares in the grid
•Choose one square of the grid at random.
•Count the population in that one square.
•Estimate the total population by multiplying the number in one square times the total squares in the grid.
RANDOM SAMPLES
Name of Population
Ducks Cattails Water Lilies
Actual Count
6 20 4
Sample Count
1 x10 = 10 3 x 10 = 30 1 x 10 = 10
ACCURACY???
Scientists help prevent over- and under-estimation by taking
several samples and averaging the results.
QUESTIONS
• Why is a sample a good way to count a population?
• What are some disadvantages to using a sample?
• What could you do to sample a population of animals that do not stay in one place?
More on Ecological Statistics…
• Population Statistics
Carrying Capacity: the maximum
population size the environment can
sustain indefinitely given food, habitat,
water, and other necessities available in
the environment