 The sum of the roots of dandelions obtained by my group in site 1 is 105 roots and site 2 is 9 roots.
 The sum of the roots of dandelions obtained by all the groups in site 1 is 325 roots and site 2 is 32 roots.
 These results are shown in percentage in the pie charts on the next page.
The percentage of the population of dandelions can be calculated by:
Sum of the roots of dandelions obtained in one site
Sum of the roots of dandelions obtained in both sites
 The percentages may not be exactly correct and representing the real density of dandelions in these two sites, such as shown in the charts: the data between the pooled and my group’s data are not the same, but with only 1% difference.

The average of the total roots obtained by all the groups can be calculated by “sum divide by the number of sampling (80)”. From this formula it arrives that, the average value for the site 1 is 325/80=4.0625roots; and site 2 is 32/80=0.4roots.
 Standard deviation can be calculated by:
Therefore, the site 1 has standard deviation of 2.570718528 and the site 2 has 0.7681145748
Conclusion and Evaluation
The density of certain organisms differ from one place to another, even though they may all grow up in the same region, i.e. two contrasting parts of a park.
Using the random sampling, with the quadrats, can give a rough idea of one area’s population or density of a certain organism, but however it is very difficult to use this method to represent the whole area, to give a very precise % of its density or population. This is because to sample an area REALLY randomly is very hard. People often have to look at a certain place and throw it or just throw it to the place that attract their sight the most/the least, this is because it is impossible to sample with shut eyes in a park, due to the fear of throwing it out of the park or onto something or someone, which may cause an accident. And also once the time for counting the number of roots in a quadrat comes, it’s sometimes also very easy to miscount one or two roots, because they are either too dense and together or too small to be seen. This is why one group’s sum of a site’s dandelions’ roots may differ from another group, just as shown in the pie charts.
The experiment can be improved by repeating the whole experiment more than 3 times to get as many results as possible or using a specific equipment for counting the number of organisms in a certain region. And if using quadrats, there is a need to shut one’s eyes and to let her to go around by herself and then throw it, to make it more random.
Even though the results between each groups differ, but as shown in the pie chart, there is only 1% difference between the sum of my group’s data and pooled data, and thus the results do follow a certain pattern, so I suggest that this experiment can be carried on universally and the results can be used reliably.