User: | Open Learning Faculty Member:
In the virtual forest tutorial, the most efficient sampling method in terms of time-spent sampling was systematic sampling as seen in the results below, however the overall difference is marginal:
- Systematic – 12 hours, 5 minutes
- Random – 12 hours, 46 minutes
- Haphazard – 12 hours, 29 minutes
Percent Error calculations for top two most common and most rare species:
| Most Common Species | Most Rare Species | |||
| Eastern Hemlock
(RF = 33.8%) |
Sweet Birch
(RF = 19.9%) |
Striped Maple
(RF = 2.8%) |
White Pine
(RF = 1.9%) |
|
| Systematic | 4.23% | 14.89% | 100% | 98.80% |
| Random | 10.30% | 25.53% | 28.57% | 50% |
| Haphazard | 0.68% | 17.02% | 42.85% | 1.19% |
*RF = Relative Frequency
For the two most common species combined the most accurate sample strategy appears to be systematic sampling (i.e.: lowest percent error calculations for both Eastern hemlock and sweet birch at 4.23% and 14.89% respectively). It should be noted that if just examining the single most common species that haphazard sampling appears to be the most accurate with Eastern hemlock receiving a remarkably low percent error of 0.68%, this is likely due to its high relative frequency in the forest. However, I would not conclude that haphazard is the best sampling strategy for common species in general since when examining the the top two most common species together systematic sampling appears to be the most accurate.
For the two most rare species combined the most accurate sampling strategy appears to be random sampling on average with striped maple having a percent error of 28.57% and white pine a percent error of 50%. Again it should be noted that haphazard sampling produced a remarkably low percent error for white pine at 1.19% but this accuracy was not reflected in the second least common species, striped maple. Overall haphazard sampling as the most accurate strategy for rare species makes very little sense since species with a very low relative frequency are statistically unlikely to be found identified with this sampling strategy and actually haphazardly sampling the correct plots to get such a low percent error repeatedly is very unlikely . That is why I would not conclude that haphazard sampling it is the best sampling strategy despite this low percent error.
Overall the accuracy declined with more rare species except for the outlier of white pine with the haphazard sampling strategy.
In total 7 species were captured with all species being captured in each sampling strategy expect for stripped maple which was not captured during the systematic sampling technique. As a result I would say that 24 samples were enough to capture the number of species in this community since almost all species were captured during all sampling techniques. However, I don’t think it was accurate enough to capture the abundance of species in each community as is shown in the percent error for white pine whose percent error varies widely from 1.19% to 50% to 98.8%.
