1: Counting
Big Populations: How do scientists
estimate the size of a large population?
You can use random sample to estimate an entire population
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?
__estimated: 35
Actual: 25___________
3: Scaling
it Up: What does it mean that we
scaled it up?
multiply the estimate of the number of the given 1m2 sample by the actual area.
4: Keeping
it Random: Why is it important to randomly select segments to count?
So that you'll avoid being biased to a certain type of segment and it's done to make your work more effective
5: When
Size Matters: What is the simplest way to determine the appropriate sample size?
simplest way to determine the appropriate sample size is to graph a running
average from the samples.
6: Bare
Bones Sampling: What is the difference
between measuring abundance versus Presence/absence?
When you count the actual number of organisms it's by abundance but when they move around and are hard to count that is presence/absence sampling.
7: Collecting
P/A Data: Counting
Moss.. How do we estimate sample
size?
we randomly pick individual points to sample, need a lot of them to get a good estimate.
8: Impervious
Surface: How do we estimate impervious
surface? Explain.
It's measured by using the presence/absence method, we have to pick up a lot of random points and calculate the percentage.
9: Getting
Fancy: What are the steps for conducting a simple transect?
Randomly select a starting point
randomly choose a direction
Lay out a transect
Determine where along the transect you will collect your sample
data
Lay out a sampling frame to collect your data from
10: Try
a Transect:
Big Populations: How do scientists
estimate the size of a large population?
You can use random sample to estimate an entire population
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?
__estimated: 35
Actual: 25___________
3: Scaling
it Up: What does it mean that we
scaled it up?
multiply the estimate of the number of the given 1m2 sample by the actual area.
4: Keeping
it Random: Why is it important to randomly select segments to count?
So that you'll avoid being biased to a certain type of segment and it's done to make your work more effective
5: When
Size Matters: What is the simplest way to determine the appropriate sample size?
simplest way to determine the appropriate sample size is to graph a running
average from the samples.
6: Bare
Bones Sampling: What is the difference
between measuring abundance versus Presence/absence?
When you count the actual number of organisms it's by abundance but when they move around and are hard to count that is presence/absence sampling.
7: Collecting
P/A Data: Counting
Moss.. How do we estimate sample
size?
we randomly pick individual points to sample, need a lot of them to get a good estimate.
8: Impervious
Surface: How do we estimate impervious
surface? Explain.
It's measured by using the presence/absence method, we have to pick up a lot of random points and calculate the percentage.
9: Getting
Fancy: What are the steps for conducting a simple transect?
Randomly select a starting point
randomly choose a direction
Lay out a transect
Determine where along the transect you will collect your sample
data
Lay out a sampling frame to collect your data from
10: Try
a Transect:
Summary: Explain
what you learned by doing this
activity
From this activity I learned how to find the estimated population easily and why it is important to know it. To start off you always need a random samples, randomness helps to be not biased which would be something negative if you were. There are three ways of sampling, the first one is abundant measuring which really is the actual number of individuals in a given area, the second is presence in which you determine many small areas to be sampled and record.The transect is simply a strip of land that runs through the area you're interested in, it's also the convenient one.
what you learned by doing this
activity
From this activity I learned how to find the estimated population easily and why it is important to know it. To start off you always need a random samples, randomness helps to be not biased which would be something negative if you were. There are three ways of sampling, the first one is abundant measuring which really is the actual number of individuals in a given area, the second is presence in which you determine many small areas to be sampled and record.The transect is simply a strip of land that runs through the area you're interested in, it's also the convenient one.