background preloader

VassarStats: Statistical Computation Web Site

VassarStats: Statistical Computation Web Site

http://vassarstats.net/

Related:  HSH216 Epidemiology & Biostatistics 2Stat

Sample Size Calculator - Confidence Level, Confidence Interval, Sample Size, Population Size, Relevant Population - Creative Research Systems This Sample Size Calculator is presented as a public service of Creative Research Systems survey software. You can use it to determine how many people you need to interview in order to get results that reflect the target population as precisely as needed. You can also find the level of precision you have in an existing sample. Before using the sample size calculator, there are two terms that you need to know. These are: confidence interval and confidence level. If you are not familiar with these terms, click here.

Sample Size Calculator by Raosoft, Inc. If 50% of all the people in a population of 20000 people drink coffee in the morning, and if you were repeat the survey of 377 people ("Did you drink coffee this morning?") many times, then 95% of the time, your survey would find that between 45% and 55% of the people in your sample answered "Yes". The remaining 5% of the time, or for 1 in 20 survey questions, you would expect the survey response to more than the margin of error away from the true answer. When you survey a sample of the population, you don't know that you've found the correct answer, but you do know that there's a 95% chance that you're within the margin of error of the correct answer. Try changing your sample size and watch what happens to the alternate scenarios. That tells you what happens if you don't use the recommended sample size, and how M.O.E and confidence level (that 95%) are related.

RStats Resources - RStats Institute Statistics Tutoring Undergraduate students who need assistance with statistics homework can receive one-on-one tutoring through Missouri State University's Bear CLAW (Center for Learning and Writing). Click here to access Bear CLAW Statistics Tutoring.

Adolescent and School Health Skip directly to search Skip directly to A to Z list Skip directly to navigation Skip directly to page options Skip directly to site content Get Email Updates To receive email updates about this page, enter your email address: CDCDASH HomeDataYRBSSData & Documentation YRBSS Data & Documentation Recommend on Facebook Tweet How To Determine Sample Size, Determining Sample Size In order to prove that a process has been improved, you must measure the process capability before and after improvements are implemented. This allows you to quantify the process improvement (e.g., defect reduction or productivity increase) and translate the effects into an estimated financial result – something business leaders can understand and appreciate. If data is not readily available for the process, how many members of the population should be selected to ensure that the population is properly represented? If data has been collected, how do you determine if you have enough data? Determining sample size is a very important issue because samples that are too large may waste time, resources and money, while samples that are too small may lead to inaccurate results.

The Central Limit Theorem To understand the wildness of samples, we would choose thousands of samples, calculate an x-bar for each, and display the x-bars in a histogram. This histogram represents a sampling distribution and when we look at it we see something truly amazing. Sampling distributions tend to be far less variable or wild than the populations they are drawn from (See Fig. 1A, 1B, 1C and 1D.) They also have essentially the same mean as the population. Logistic Regression Preliminaries Model Formulae You will need to know a bit about Model Formulae to understand this tutorial. Deriving Z-Test Formulas: 1-Sample, 1-Sided in Derivation, Normal, z-test, one-sample, one-sided Setup We will derive the formulas for three situations: Normal, Binomial, and Poisson data.

StatThink - Statistical Thinking Diagrams and Models From: Pfannkuch, M., Regan, M., Wild, C. and Horton, N.J. (2010) Telling Data Stories: Essential Dialogues for Comparative Reasoning.Journal of Statistics Education, 18(1). Looking at data Download as a png or an eps Statistics Formulas This web page presents statistics formulas described in the Stat Trek tutorials. Each formula links to a web page that explains how to use the formula. Parameters Statistics Unless otherwise noted, these formulas assume simple random sampling. Correlation How do I determine whether my data are normal? From PsychWiki - A Collaborative Psychology Wiki How do I determine whether my data are normal? There are three interrelated approaches to determine normality, and all three should be conducted. Look at a histogram with the normal curve superimposed. A histogram provides useful graphical representation of the data. - To provide a rough example of normality and non-normality, see the following histograms. The black line superimposed on the histograms represents the bell-shaped "normal" curve.

Australian Statistical Geography Standard (ASGS) The Australian Statistical Geography Standard (ASGS) provides a framework of statistical areas used by the Australian Bureau of Statistics (ABS) and other organisations to enable the publication of statistics that are comparable and spatially integrated. First introduced in 2011, the ASGS replaced the Australian Standard Geographical Classification (ASGC) that had been in use since 1984. The ASGS provides users with an integrated set of standard areas that they can use to access, visualise, analyse and understand statistics produced by the ABS and other organisations. The ASGS is split into two parts, the ABS Structures and the Non ABS Structures.

IBM Knowledge Center - One-Way ANOVA Post Hoc Tests United States IBM Knowledge Center Site map Marketplace Help Online - Origin Help - Interpreting Results of Discriminant Analysis DiscAnalysis-Result Discriminant Report Sheet Descriptive Statistics

Related: