In this insert we present programs to perform several procedures designed to estimate the parameters of the von Bertalanffy growth function. Three of them are linear derivations from the basic growth equation, and the last one uses a nonlinear regression Read More …
Categoría: CAPÍTULOS
Nonparametric assessment of multimodality for univariate data
In previous inserts we presented a series of programs to calculate density estimates for univariate data (Salgado-Ugarte et al. 1993, 1995a). We also introduced a series of practical bandwidth rules for histograms, frequency polygons, and kernel density estimators, including cross-validation Read More …
ASH, WARPing, and kernel density estimation for univariate data
Kernel density estimators are important tools for exploring and analyzing data distributions (see the references in Salgado-Ugarte et al. 1993). However, one drawback of these procedures is the large number of calculations required to compute them. As a consequence, it Read More …
Practical rules for bandwidth selection in univariate density estimation
The choice of bandwidth (smoothing parameter) is one of the central problems of density estimation. As we noted in previous inserts (Salgado-Ugarte et al. 1993, 1995), there are several ways to select an appropriate value for this parameter for histograms, Read More …
Semigraphical determination of Gaussian components in mixed distributions
Mixed distributions -mixtures of normal distributions- arise frequently in biological and ecological data, and the analysis of these mixed distributions is an important topic in fisheries science, particularly when studying species in subtropical and tropical areas. Many samples of fish Read More …
Exploring the shape of univariate data using Kernel density estimators
This insert introduces some kernel estimators that provide nonparametric density estimates along with ado-files to calculate them. Kernel density estimators are an essential component of many more complicated estimators, such as semiparametric procedures. In this insert, we will stress the Read More …
Twice reroughing procedure for resistant nonlinear smoothing
The smtwice ado-file for a nonlinear resistant smoother presented in sed7 (Salgado-Ugarte and García 1992) is included on the STB diskette. A new version of the ado-file sm4253eh for Stata 3.0 has been prepared and may be installed in place Read More …
Resistant smoothing using Stata
As has been shown in several articles in the STB (Geiger 1991; DeLeon and Anagnoson 1991), one of the main purposes of exploratory data analysis (EDA) techniques is the finding of trends and patterns that are nonlinear. Science and other Read More …