1: Counting Big Populations: How do scientists estimate the size of a large population?
having a way to estimate the large proportion- take a random sample.
2: Sampling on a grid: To count the dandelions, we'll first create a grid, then use the computer's random number generator to tell us which grid squares to count. We'll do this 10 times, because,as you'll see, the counts in the different grid squares will vary a lot. After you count 10 squares,you'll use the average number per square to estimate the population of the entire lawn.
How many dandelions are there on the grid?
97
3: Scaling it Up: What does it mean that we scaled it up?
multiply the estimated # by the amount of squares
4: Keeping it Random: Why is it important to randomly select segments to count?
The species need an equal chance to be selected
5: When Size Matters: What is the simplest way to determine the appropriate sample size?
graph a running average.
6: Bare Bones Sampling: What is the difference between measuring abundance versus Presence/absence?
Abundance is the actual number of individuals given in an area.
Presence/absence is when you determine many small areas to be sampled and record whether the organism was recorded or not.
7: Collecting P/A Data: Counting Moss.. How do we estimate sample size?
pick any points on the area and see if that point is on any moss after 10 spots, find the percentage that the point was on moss.
8: Impervious Surface: How do we estimate impervious surface? Explain.
using the presence/absence method, We pick points on the map and find out if the surface is impervious.
9: Getting Fancy: What are the steps for conducting a simple transect?
Randomly select a point,Randomly choose a direction,Lay out a transect,Determine where along the transect you will collect sample data,Layout a sampling frame
10: Try a transect:
Yes!
Average # dandelions in a sampared to a baseline of 1.0. So the % increase = 2.7/1.0=270%
Summary: Explain what you learned by doing this activity
One method is abundant measuring, in this method we just counting the number of individual organisms in a given area. Another one is presence/absence, in this method you will look at small areas and determine if an organism was observed or not. The last is transect, this method has five steps, which are randomly select a starting point, randomly choose a direction, lay out a transect , where along the transect you will collect your sample data, and laying out a sampling frame.
having a way to estimate the large proportion- take a random sample.
2: Sampling on a grid: To count the dandelions, we'll first create a grid, then use the computer's random number generator to tell us which grid squares to count. We'll do this 10 times, because,as you'll see, the counts in the different grid squares will vary a lot. After you count 10 squares,you'll use the average number per square to estimate the population of the entire lawn.
How many dandelions are there on the grid?
97
3: Scaling it Up: What does it mean that we scaled it up?
multiply the estimated # by the amount of squares
4: Keeping it Random: Why is it important to randomly select segments to count?
The species need an equal chance to be selected
5: When Size Matters: What is the simplest way to determine the appropriate sample size?
graph a running average.
6: Bare Bones Sampling: What is the difference between measuring abundance versus Presence/absence?
Abundance is the actual number of individuals given in an area.
Presence/absence is when you determine many small areas to be sampled and record whether the organism was recorded or not.
7: Collecting P/A Data: Counting Moss.. How do we estimate sample size?
pick any points on the area and see if that point is on any moss after 10 spots, find the percentage that the point was on moss.
8: Impervious Surface: How do we estimate impervious surface? Explain.
using the presence/absence method, We pick points on the map and find out if the surface is impervious.
9: Getting Fancy: What are the steps for conducting a simple transect?
Randomly select a point,Randomly choose a direction,Lay out a transect,Determine where along the transect you will collect sample data,Layout a sampling frame
10: Try a transect:
Yes!
Average # dandelions in a sampared to a baseline of 1.0. So the % increase = 2.7/1.0=270%
Summary: Explain what you learned by doing this activity
One method is abundant measuring, in this method we just counting the number of individual organisms in a given area. Another one is presence/absence, in this method you will look at small areas and determine if an organism was observed or not. The last is transect, this method has five steps, which are randomly select a starting point, randomly choose a direction, lay out a transect , where along the transect you will collect your sample data, and laying out a sampling frame.