Internet resources to accompany:
Monitoring Plant and Animal Populations
Statistics Links for:
Using DSTPLAN and PC-SIZE
Using NCSS PROBABILITY CALCULATOR
Online Statistical Tables and
Probability Calculators
- Surfstat
Statistical Tables - Online calculator will report the statistic given
the probability or report the probability given the statistic for the
Student's t distribution, the chi-squared distribution, and the standard
normal distribution. For example, you can type in the degrees of freedom and
the value of t calculated from a t test and the calculator will report the
probability.
- Distribution
calculator from UCLA stats page - Calculates the statistic give the
probability or the probability given the statistic. A large number of
choices are available (can be confusing; note Student = t distribution).
- Distribution
calculator from VassarStats (Richard Lowry, Vassar College) - Given the
degrees of freedom, presents a graph of the distribution as well as critical
values of the statistic (for the one and two-tailed condition). Includes
chi-square distribution, t distribution, and F distribution.
- Simple Interactive
Statistical Analysis Page - Online calculator will report the statistic
given the probability or report the probability given the statistic for the
Student's t distribution, the chi-squared distribution, the F distribution,
and the standard normal distribution (z). Clear directions and explanations.
- Printable
statistics tables - A complete assortment (t, chi-square, normal, F
distributions) in Adobe Acrobat PDF format.
- NCSS Probability Calculator
- A probability calculator that can be downloaded to your computer. Given
the calculated value of a statistic from a statistical test, NCSS
probability calculator will provide the corresponding probability value.
Sample Size Determination for
Point Estimates (target/threshold objectives)
Sample Size and Power
Calculations for Change/trend objectives
- A
comprehensive list of power analysis software for microcomputers - Len
Thomas' (School of Mathematical and Computational Sciences, University of
St. Andrews, Scotland) power analysis web site. Includes links to a
multitude of software for power analysis and sample size determination.
- Thomas, L. and C. Krebs. 1997. A
review of statistical power analysis software - Online paper published
in the Bulletin of the Ecological Society of America 78 (2): 126-139.
- Power
calculator by University of California Los Angeles - An online
calculator that reports sample size for a given power or power for a given
sample size for several designs (normal, binomial, one or two-tailed, equal
or unequal sample sizes).
- Power and
sample size calculations and graphics - Page by Russ Lenth, Division of
Mathematical Sciences, the College of Liberal Arts or The University of
Iowa. Provides informative interactive graphics that allow you to change
sample size or effect size or alpha value and see the change in power of
your design. Easy to use and interpret. Includes helps, notes and
suggestions. Java applets available for a single proportion (compared to a
target), two proportions, paired and independent means (t tests) and a
balanced ANOVA.
- Statistical Solution's
Difference in two proportions or means (independent samples) - Allows
you to select alpha and power. Can accept unequal sample sizes. Provides an
attractive output.
Descriptive Statistics
Calculation and Graphical Presentation
- John Pezzullo's
excellent stats page contains a well-organized section of annotated links to
sites that perform these types of calculations.
Confidence Interval
Calculations
- Confidence interval
calculation from Arizona State University - Calculates confidence
intervals for a mean, a proportion, and the difference between two
independent means.
- Exact Binomial
Confidence Intervals - John C. Pezzullo's calculator. While default is
the 95% confidence level, can select other levels or even asymmetrical
levels. Can also download as an Excel add-in.
- BINOM -
Charles J. Krebs, described in Ecological Methodology (1999). Fit a
Distribution (NEGBINOM, POISSON, BINOM) fit a negative binomial, poisson, or
binomial distribution to quadrat count data; program can choose
"best" fitting distribution . Unfortunately, these programs use a
brain-dead way of storing distributions, with storage proportional to the
largest count, so they only work for small counts (no more than 180 or so).
A number of other programs can be found at this site: clustering (for
classification), Jolly-Seber mark-recapture, diversity indices, and a test
for differences in means from two samples using a randomization test.
- Confidence
Interval for Proportions from VassarStats - Calculates the 95%
confidence interval of a proportion (with and without continuity correction)
and the confidence interval of the difference between two independent
proportions. (Under "proportions" accessed from main page).
- Confidence
Interval for the Median - A tabular approach. Clear explanation and
simple to use.
- SampleCalc:
confidence intervals for complex sampling designs - Peter Tryfos,York
University. The program SampleCalc (short for Sample Calculator) is a
Microsoft EXCEL add-in that calculates unbiased point estimates and
approximate confidence intervals of the principal population characteristics
for each specified variable and each category of specified attributes under
simple, stratified, two-stage, and cluster random sampling. It is assumed
throughout that sampling is without replacement. The methodology is
described in, among other sources, Peter Tryfos, Sampling for Applied
Research: Text and Cases, Wiley, 1996, Chs. 3 to 5. From the website: This
book is "an applied, one-semester introduction to sampling methods for
non-mathematics majors that uses simple numerical illustrations to provide
an intuitive understanding of concepts and confirm major results. The text
describes various methods for sample selection and estimation including
unequal probability sampling and the prediction approach." Includes
many examples and problems (with answers) and can serve as a self-study
course.
- Rcalc
-- a stand-alone Windows-based program that conducts the same types of
calculations. It updates a DOS version include with Sampling for Applied
Research: Text and Cases, Wiley, 1996.
Hypothesis Tests
- University of
California Los Angeles - Calculates a one-tailed or two-tailed t-test
for paired or independent samples. It can either look up the P value for t,
or it can compute the P value using resampling. Type or paste (from a
spreadsheet) original data, not summary data.
- Arizona State University - calculator conducts the paired
t-test and independent
sample t-test. Enter summary info (mean, standard deviation).
- Vassar Stats
- Richard Lowry, Vassar College. Can enter data on the site or by cutting
and pasting from data already entered into a spreadsheet. Conducts paired
and independent t tests, ANOVA (3 and 4 independent samples).
- Graphpad - Online
calculators for paired and unpaired t tests, McNemar's test. Includes links
to online text, as well as a section on selecting the proper analysis. Enter
or paste original data or summary values (mean, standard deviation).
- IFA
(University of the Netherlands) - McNemar's Test. Includes explanation and
discussion.
- Simple Interactive
Statistical Analysis - Computes t test (paired) and McNemar's test (and
nonparametric Wilcoxon) given entry of summary statistics (e.g. mean,
standard deviation). Includes discussion and explanation.
- 2x2 contigency
table (chi-square) - Computes chi-square test. Requires input of
observed frequencies for two years of data (example given is a medical one),
and selected critical probability (90-99%).
- 2x2
contigency table (chi-square) - Computes chi-square test. Requires input
of observed frequencies for two years of data. Prepares an attractive table
and lists the calculated chi-square value and its probability.
- For larger contingency tables see the Georgetown Linguistics Web Chi
Square Calculator
Non-parametric Tests
Resampling Methods
- Vassar Stats
- Resampling probability estimates for the difference between the means of
two independent samples. You enter the data for each sample on the screen.
(Under Miscellanea)
- Resampling Stats Homepage - Large
number of links to resampling subjects
Freeware/shareware (and some
commercial) stats programs
- Webstat - Program
runs through your browser or can be downloaded and run off-line. Can enter
and save data, or paste from a file. Conducts all the tests described in the
Handbook, and produces acceptable graphics.
- Statlets
- A collection of Java Applets that you can run through your browser. Enter
data or past from a file. Conducts all the tests described in the Handbook,
and produces a large assortment of graphics.
- Statpoint Online
Computing Center - Visitors can enter and analyze up to 50 rows and 8
columns of data. Includes descriptive statistics, graphical presentation,
statistical tests for paired and unpaired means. Includes routines for
calculating sample size and power.
- Statistical Analysis Software (Modstat)
- A stats package created by a statistics instructor, Dr. Robert C. Knodt,
available for $22. Completes nearly 300 statistical routines. Free two-month
trial available.
- Openstat - Freeware
available from Dr. Bill Miller, Professor Emeritus, Iowa State University.
Site also includes draft chapters of a textbook.
- Links
to Statistical Freeware/shareware software - John Pezzullo's page
contains an extremely well-organized annotated list of links to statistical
freeware, as well as links to demos and short-term trial use software.
- Rainer
Wuerlaender hosts a comprehensive list of freeware and commercial
statistical software.
Online Statistics Texts
- Hyperstat online
- An online statistics text arranged by subjects into chapters. Subjects are
accompanied by hyperlinked glossary, links to online calculation and
analysis tools, and links to other online texts.
- Statsoft's
Basic Statistics - Online extensive text with hyperlinked glossary
- Concepts and
Applications of Inferential Statistics - Extensive and occasionally
interactive statistics textbook. It is a companion site of VassarStats, a
popular computation link in earlier sections on this stats page.
- Introductory Statistics:
Concepts, Models, and Applications - Online text by David W. Stockburger,
Southwest Missouri State University
- The
Data Analysis Briefbook - "The BriefBook is a condensed handbook,
or an extended glossary, written in encyclopedic format, covering subjects
in statistics, computing, analysis, and related fields. It intends to be
both introduction and reference for data analysts, scientists and
engineers."
- Statistics at
Square One - Basic stats book covers most of the concepts introduced in
the Handbook. Lacks hyperlinks within the text.
- Surfstat
Australia - Basic stats book. Lacks hyperlinks within the text, but easy
to read and well illustrated with figures.
General Statistics Sites