1: Counting Big Populations: How do scientists estimate the size of a large population?
They take random samples.
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? 94
3: Scaling it Up: What does it mean that we scaled it up?
Once you have a mean for your sample area you can multiply that by how many squares you have on a map
4: Keeping it Random: Why is it important to randomly select segments to count?
To avoid experimenter's bias
5: When Size Matters: What is the simplest way to determine the appropriate sample size?
To create a graph average
6: Bare Bones Sampling: What is the difference between measuring abundance versus Presence/absence?
Abundance is the actual number of individuals in a given area
Presence/absence small areas to be sampled and record whether the organism was observed or not.
7: Collecting P/A Data: Counting Moss.. How do we estimate sample size?
Randomly pick individual spots samples to
8: Impervious Surface: How do we estimate impervious surface? Explain.
9: Getting Fancy: What are the steps for conducting a simple transect?
1. Select a random spot
2. Randomly select a direction
3. Lay out the transect
4. Lay out a frame
They take random samples.
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? 94
3: Scaling it Up: What does it mean that we scaled it up?
Once you have a mean for your sample area you can multiply that by how many squares you have on a map
4: Keeping it Random: Why is it important to randomly select segments to count?
To avoid experimenter's bias
5: When Size Matters: What is the simplest way to determine the appropriate sample size?
To create a graph average
6: Bare Bones Sampling: What is the difference between measuring abundance versus Presence/absence?
Abundance is the actual number of individuals in a given area
Presence/absence small areas to be sampled and record whether the organism was observed or not.
7: Collecting P/A Data: Counting Moss.. How do we estimate sample size?
Randomly pick individual spots samples to
8: Impervious Surface: How do we estimate impervious surface? Explain.
9: Getting Fancy: What are the steps for conducting a simple transect?
1. Select a random spot
2. Randomly select a direction
3. Lay out the transect
4. Lay out a frame
10: Try a Transect:
Summary: Explain what you learned by doing this activity
I've learned that depending on what kind of data you want to collect, depends on what form of collecting data would be appropriate. Even if you collect the data correctly you will still be a few and if your unlucky you'll be extremely off. Nature is very complicated to measure.
Summary: Explain what you learned by doing this activity
I've learned that depending on what kind of data you want to collect, depends on what form of collecting data would be appropriate. Even if you collect the data correctly you will still be a few and if your unlucky you'll be extremely off. Nature is very complicated to measure.