Sampling is a computer tool designed to help biology students obtain a qualitative understanding of basic concepts related to estimation and statistics. Sampling presents the user with a group of hypothetical populations distributed throughout an area, and with tools for sampling these populations to estimate characteristics such as population size and density, the nature of each populationís spatial patterning, and spatial correlations in abundance between populations. By manipulating the number of samples, the size of each sample, and the spatial location and patterning of samples, users of Sampling can investigate important questions in population estimation and, especially in conjunction with field studies, develop a much deeper understanding of fundamental concepts than would likely be obtained solely from limited field studies that can be conducted in introductory courses.
Sampling has an easy-to-use interface that allows the user to rapidly and intuitively sample a group of populations, and to immediately see results in graphical or tabular format. For example, Sampling presents you with an aerial view of the populations, the Species Distribution window, shown below. By simply placing the cursor over a particular spot, and clicking the mouse, students can place a quadrat over a given area. When the mouse button is released, Sampling will calculate the numbers of each species in the quadrat. Each time a new quadrat is created, Sampling will immediately update estimates of population statistics and will update any relevant graphs (such as frequency distributions) based on the new information.
The Statistics window presents the mean density per quadrat, the variance, the standard deviation, and the standard error for each population. The Frequency Distribution window (shown below) displays a bar graph with the horizontal axis representing the number of individuals of each species (divided up into fixed intervals, such as 0-5, 5-10), and the vertical axis representing the number of quadrats having population numbers in each interval.
The user can change the number of species displayed in the Species Distribution window (and therefore sampled), the size and shape of quadrats, the interval size used for the horizontal axis in the frequency distribution graph, and the pattern of the spatial distribution of populations (random, clumped, or even; the latter is not implemented in this version of Sampling).
Macintosh and Power Macintosh