How Big is My Population?
1: Counting Big Populations: How do scientists estimate the size of a large population?
Scientists estimate the size of a large population by having a way to estimate the large proportion by taking 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? 92
3: Scaling it Up: What does it mean that we scaled it up?
We multiply the estimated number by the amount of squares on the grid
4: Keeping it Random: Why is it important to randomly select segments to count?
The species need an equal chance to be selected and to keep from having experimenter's bias.
5: When Size Matters: What is the simplest way to determine the appropriate sample size?
The simplest way to determine the appropriate sample size is to 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?
You can estimate sample size by picking random individual points
8: Impervious Surface: How do we estimate impervious surface? Explain.
You can measure impervious surface by using the P/A method. You would pick random points in an area and determine how many of them have an impervious surface
9: Getting Fancy: What are the steps for conducting a simple transect?
1.) Randomly select a point
2.) Randomly choose a direction
3.) Lay out a transect
4.) Determine where along the transect you will collect sample data
5.) Layout a sampling frame
10: Try a Transect:
Scientists estimate the size of a large population by having a way to estimate the large proportion by taking 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? 92
3: Scaling it Up: What does it mean that we scaled it up?
We multiply the estimated number by the amount of squares on the grid
4: Keeping it Random: Why is it important to randomly select segments to count?
The species need an equal chance to be selected and to keep from having experimenter's bias.
5: When Size Matters: What is the simplest way to determine the appropriate sample size?
The simplest way to determine the appropriate sample size is to 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?
You can estimate sample size by picking random individual points
8: Impervious Surface: How do we estimate impervious surface? Explain.
You can measure impervious surface by using the P/A method. You would pick random points in an area and determine how many of them have an impervious surface
9: Getting Fancy: What are the steps for conducting a simple transect?
1.) Randomly select a point
2.) Randomly choose a direction
3.) Lay out a transect
4.) Determine where along the transect you will collect sample data
5.) Layout a sampling frame
10: Try a Transect:
Summary: Explain what you learned from doing this activity
Doing this activity, I learned that here are many different types of ways for estimating a population. Theirs abundant which is when you count individuals in a given area. Presence/absence where you look at small areas and find if the organism was observed or not. Lastly there's transect which is done first off by selecting a point then you select a direction and lay out a transect. It also uses frames to measure populations.
Doing this activity, I learned that here are many different types of ways for estimating a population. Theirs abundant which is when you count individuals in a given area. Presence/absence where you look at small areas and find if the organism was observed or not. Lastly there's transect which is done first off by selecting a point then you select a direction and lay out a transect. It also uses frames to measure populations.