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TrendPowerTool: A web lookup tool for estimating the statistical power of a monitoring program to detect population trends

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By Upper Midwest Environmental Sciences Center January 12, 2021

A simulation-based power analysis can be used to estimate the sample sizes needed for a successful monitoring program, but requires technical expertise and sometimes extensive computing resources. We developed a web-based lookup app, called TrendPowerTool, to provide guidance for ecological monitoring programs when resources are not available for a simulation-based power analysis (Fig. 1). TrendPowerTool is implemented through the shiny package in R, but is accessible through a webpage without the need for users to install any added software. By drawing on results of 1.4 million scenarios that we simulated on a supercomputer, TrendPowerTool quickly and easily provides estimates of the statistical power to detect a population trend of a particular magnitude for a planned monitoring program (e.g., Fig. 2), based on user-specified parameters for the monitoring design and population of interest. TrendPowerTool provides a user-friendly interface that retrieves results instantaneously, facilitating the important step of conducting a power analysis when designing monitoring programs.

Web Tools

Web Tools

Plot depicting power to detect a trend of -4% per year over 5 years at various sample sizes.
Sources/Usage: Public Domain. View Media Details
Figure 1. Plot depicting power to detect a trend of -4% per year over 5 years at various sample sizes.

 

Figure 2. Estimates of statistical power at varying levels of trend made possible by TrendPowerTool for four example datasets
Sources/Usage: Public Domain. View Media Details
Figure 2. Estimates of statistical power at varying levels of trend made possible by TrendPowerTool for four example datasets (see Weiser et al. 20xx for further details).

A simulation-based power analysis can be used to estimate the sample sizes needed for a successful monitoring program, but requires technical expertise and sometimes extensive computing resources. We developed a web-based lookup app, called TrendPowerTool, to provide guidance for ecological monitoring programs when resources are not available for a simulation-based power analysis (Fig. 1). TrendPowerTool is implemented through the shiny package in R, but is accessible through a webpage without the need for users to install any added software. By drawing on results of 1.4 million scenarios that we simulated on a supercomputer, TrendPowerTool quickly and easily provides estimates of the statistical power to detect a population trend of a particular magnitude for a planned monitoring program (e.g., Fig. 2), based on user-specified parameters for the monitoring design and population of interest. TrendPowerTool provides a user-friendly interface that retrieves results instantaneously, facilitating the important step of conducting a power analysis when designing monitoring programs.

Web Tools

Web Tools

Plot depicting power to detect a trend of -4% per year over 5 years at various sample sizes.
Sources/Usage: Public Domain. View Media Details
Figure 1. Plot depicting power to detect a trend of -4% per year over 5 years at various sample sizes.

 

Figure 2. Estimates of statistical power at varying levels of trend made possible by TrendPowerTool for four example datasets
Sources/Usage: Public Domain. View Media Details
Figure 2. Estimates of statistical power at varying levels of trend made possible by TrendPowerTool for four example datasets (see Weiser et al. 20xx for further details).
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