Quadrat Random Sampling Investigation

Name__________________________________ Period____ Date_________ Quadrat Random Sampling Investigation Scientists cannot possibly count every organism in a population. One way to estimate the size of a population is to collect data by taking random samples. In this activity, you will look at how data obtained from random sampling compare with data obtained by an actual count. Procedure: Go to the following website https://www.calculatorsoup.com/calculators/statistics/number-generator.php 1. Create a sample size of 10. 2. Sample range 1-10, calculate, allow duplicates, write down in order your answer 8 4 4 5 2 5 2289 3.Sample range A-J, allow duplicates, calculate, write down in order your answer DGGGGCJHGJ The grid shown below represents a meadow measuring 10 m on each side. Each grid segment is 1m x 1m. Each black circle represents one sunflower plant. 4. Write down your random sample grid segments into the data table 2111241341 5. Find the total number of sunflower plants for the 10 segment sample. This is an estimation based on a formula. Add all the grid segment sunflowers together and divide by ten to get an AVERAGE number of sunflower plants per grid segment. Record this number in the table. Multiple the average number of sunflower plants by 100 (this is the total number of grid segments) to find the total number of plants in the meadow based on your sample. Record this number in your data table 6. Now count all the sunflower plants actually shown in the meadow. Record this number in the data table. Divide this figure by 100 to calculate the average number of sunflower plants per each grid. ​ Random Sampling Data Grid Segment​ (number-letter) Number of​ Sunflowers 8-d 2 4-g 1 4-g 1 5-g 1 2-g 2 5-c 4 2-j 1 2-h 3 8-g 4 1 9-j Total number of sunflowers in sampled grids___20___ Average per grid (divide total in sampled grids by 10) _2____ Total estimated number of plants in meadow (multiply average by 100)__200___ Actual Data Total number of Sunflowers ___ _195__ ​ (count by hand) Average number of Sunflowers (divide total number by 100)​ Per grid __1.95___ Analysis: 1. Compare the total number you got for sunflowers from the SAMPLING to the ACTUAL count. How close are they? The total number from sampling and the actual count were similar, as the sampling # was 5 off from the actual count. 2. Why was the number generator used to select the grid segments? We use the number generator, so there is no bias in what box we pick, and its completely random. 3. Why do biologists use Sampling? Why can’t they just go into the forest and count all the sunflower plants? Biologists use saplings because it's much easier and quicker than counting every single sunflower plant. It's also easier to miscount and make mistakes when counting every individual plant. 4. Population Sampling is usually more effective when the population has an even dispersion pattern. It is less effective when clumped dispersion patterns are present. Explain why this would be the case. An even dispersion pattern is more effective than a clumped dispersion pattern because you can clearly distinguish the individuals present. Compared to a clumped dispersion where everything is closely together, it can be harder to tell what is one, and not just a group. 5. In a forest that measures 5 miles by 5 miles, a sample was taken to count the number of silver maple trees in the forest. The number of trees counted in the grid is shown below. The grids where the survey was taken were chosen randomly. Determine how many silver maple trees are in this forest using the random sampling technique. Show your work! 7 3 5 11 9 Add all the numbers in the grid together to find total 7+11+9+5+3=35 Then divide the total number by 5 to get the average amount in each grid 35/5=7 Multiply by 25 since it's a 5 by 5 grid to get the total estimated number 7x25=175 Total # of silver maple trees = 175