Estimate total species richness using the improved Chao1 estimator (Chiu et al. 2014). Uses singletons through quadrupletons (f1–f4) to reduce bias for small samples.
Value
An object of class spacc_estimate with components:
- estimator
Name of the estimator (
"iChao1")- estimate
Estimated total richness
- se
Standard error of the estimate
- lower
Lower 95 percent confidence bound
- upper
Upper 95 percent confidence bound
- S_obs
Observed species richness
- details
List with
f1,f2,f3,f4
Details
The improved Chao1 estimator adds a correction term using f3 and f4: $$S_{iChao1} = S_{Chao1} + \frac{f_3}{4 f_4} \max\left(f_1 - \frac{f_2 f_3}{2 f_4}, 0\right)$$
When \(f_4 = 0\), the estimator collapses to Chao1.