Blog Post 4: Sampling Strategies
In my field research project, I utilized three different sampling strategies: systematic, random, and haphazard sampling. The objective was to compare their efficiency in terms of time spent and accuracy in estimating the abundance of dandelions (Taraxacum officinale) in a forested park area near Mississauga, ON. Here’s a summary of my findings from this exercise.
Sampling Strategies and Time Efficiency
- Systematic Sampling: This method involved placing quadrats at regular intervals along a transect line. It was the most time-efficient, taking 4 hours and 10 minutes to complete. Systematic sampling provides a structured approach that ensures coverage of the study area, but it may miss variations in species abundance if the regular intervals coincide with patterns of distribution.
- Random Sampling: Quadrats were placed randomly throughout the study area. This method took 4 hours and 45 minutes to complete. Random sampling is useful for avoiding biases, but it can be less efficient as it may result in uneven coverage of the area.
- Haphazard Sampling: This method involved placing quadrats in a non-systematic, casual manner, which took 4 hours and 30 minutes. Haphazard sampling is the least structured and can lead to significant biases, particularly if certain areas are unconsciously favoured.
Accuracy and Percentage Error
The accuracy of each sampling method was measured by calculating the percentage error in estimating dandelion abundance for both common and rare instances in the study area.
| Sampling Strategy | Time Spent | Common Species % Error | Rare Species % Error |
|---|---|---|---|
| Systematic | 4 hr, 10 min | 14.5% | 75.3% |
| Random | 4 hr, 45 min | 12.0% | 67.9% |
| Haphazard | 4 hr, 30 min | 100.0% | 100.0% |
- Systematic Sampling: Had a moderate percentage error for common species (14.5%) but a significantly higher error for rare species (75.3%). The regular interval placement may have missed certain clusters of rare dandelions, leading to an underestimation of their abundance.
- Random Sampling: Showed the best balance between time and accuracy, with a 12.0% error for common species and a 67.9% error for rare species. Although it was the slowest method, it provided a more accurate estimate for both common and rare species due to the random placement of quadrats.
- Haphazard Sampling: Had the highest percentage error, at 100% for both common and rare species. This method’s lack of structure and potential biases made it the least reliable, despite being relatively time-efficient.