Sample Planning Wizard

    Right now, somewhere, a survey research study is failing. Sponsors are spending too much, and analysts are drawing wrong conclusions - all because the sampling plan did not fit the research needs.  

The solution:  Stat Trek's Sample Planning Wizard. Using a friendly, step-by-step approach, the Wizard provides expert advice online.

• Which sampling method should I use?
• How large a sample size do I need?
• What is the margin of error?
• What is the power of the design?
• How can I get the best results at the lowest cost?

The Sample Planning Wizard answers all of these questions and more. Whether you're just starting out or have years of survey sampling experience, the Sample Planning Wizard provides all of the help you need to create powerful, cost-effective sampling plans.

The Sample Planning Wizard is available only to registered users. > Register now

Sample Planning Wizard | Demo

Statistics and Probability Tutorial

    The statistics and probability tutorial is free. It requires only an understanding of arithmetic (addition, subtraction, multiplication, division), as well as basic algebra. It is for you if:

• You are new to statistics or you want to refresh dormant skills.
• You want to solve common statistical problems without having to call somebody for help.

The tutorial walks you through skills step by step, at your own pace. Examples and sample problems reinforce learning. Lessons explain technical terms in "aw shucks" language, so you are never confused by statistical jargon.

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Advanced Placement (AP) Statistics Tutorial

    The Advanced Placement (AP) statistics tutorial is free. It covers each of the topics that make up the Advanced Placement (AP) Statistics curriculum.

• Exploring data. Describing patterns and departures from patterns.
• Sampling and Experimentation: Planning and conducting a study.
• Anticipating Patterns: Exploring random phenomena using probability and simulation.
• Statistical Inference: Estimating population parameters and testing hypotheses.

Topics are introduced in short, easy-to-understand lessons. Practice and review questions help you prepare for the Advanced Placement (AP) Statistics exam. And on-line Help is just a mouse click away.

Go to Advanced Placement (AP) Statistics Tutorial

Advanced Placement (AP) Statistics Practice Exam

    The Advanced Placement (AP) statistics practice exam is free. This is a practice test for the multiple-choice section of the Advanced Placement (AP) Statistics Exam. Like the actual AP Statistics Exam, this test includes 40 questions covering a variety of topics.

• Results are scored and reported automatically, as you take the test.
• Detailed explanations are provided for each test question.

To improve your skill level, review the answer to each question that causes you difficulty.

Go to Advanced Placement (AP) Statistics Practice Exam

Statistics and Probability Glossary

    The glossary is free. It provides clear explanations of all the statistical terms used on the Stat Trek web site. In many cases, it also provides links to related information. To access the glossary, click the "Help" link that appears in the header of every Stat Trek web page.

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Normal Calculator

    The Normal Calculator is free. It solves common statistical problems, based on the normal distribution. The normal calculator:

• Finds cumulative probability, given the normal random variable.
• Finds the normal random variable, given the cumulative probability.
• Works with both the general normal distribution and the standard normal distribution.

Clear, intuitive instructions guide you to an accurate solution, quickly and easily. If anything is unclear, frequently-asked questions and sample problems provide straightforward explanations.

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t Distribution Calculator

    The t Distribution Calculator is free. It solves common statistical problems, based on the t distribution. The t distribution calculator:

• Finds cumulative probability, given the t random variable.
• Finds the t random variable, given the cumulative probability.
• Works with both the general t distribution and the standard t distribution.

Clear, intuitive instructions guide you to an accurate solution, quickly and easily. If anything is unclear, frequently-asked questions and sample problems provide straightforward explanations.

Go to t Distribution Calculator

Binomial Calculator

    The Binomial Calculator is free. Compute binomial probabilities - simple probabilities and cumulative probabilities. Clear, intuitive instructions guide you to an accurate solution, quickly and easily. If anything is unclear, frequently-asked questions and sample problems provide straightforward explanations.

Go to Binomial Calculator

Negative Binomial Calculator

    The Negative Binomial Calculator is free. Compute negative binomial probabilities. Clear, intuitive instructions guide you to an accurate solution, quickly and easily. If anything is unclear, frequently-asked questions and sample problems provide straightforward explanations.

Go to Negative Binomial Calculator

Multinomial Calculator

    The Multinomial Calculator is free. Compute multinomial probability. Clear, intuitive instructions guide you to an accurate solution, quickly and easily. If anything is unclear, frequently-asked questions and sample problems provide straightforward explanations.

Go to Multinomial Calculator

Hypergeometric Calculator

    The Hypergeometric Calculator is free. Compute hypergeometric probabilities - simple probabilities and cumulative probabilities. Clear, intuitive instructions guide you to an accurate solution, quickly and easily. If anything is unclear, frequently-asked questions and sample problems provide straightforward explanations.

Go to Hypergeometric Calculator

Poisson Calculator

    The Poisson Calculator is free. Compute probabilities based on a Poisson distribution - simple probabilities and cumulative probabilities. Clear, intuitive instructions guide you to an accurate solution, quickly and easily. If anything is unclear, frequently-asked questions and sample problems provide straightforward explanations.

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Chi-Square Calculator

    The Chi-Square Calculator is free. Compute cumulative probability based on the chi-square distribution. Clear, intuitive instructions guide you to an accurate solution, quickly and easily. If anything is unclear, frequently-asked questions and sample problems provide straightforward explanations.

Go to ChiSquare Calculator

F Distribution Calculator

    The F Distribution Calculator is free. Compute cumulative probability based on the F distribution, or find the F statistic based on the cumulative probability. Clear, intuitive instructions guide you to an accurate solution, quickly and easily. If anything is unclear, frequently-asked questions and sample problems provide straightforward explanations.

Go to F Distribution Calculator

Probability Calculator

    The Probability Calculator is free. Compute the unknown probability of an event, based on the known probability of other related events. The Probability Calculator guides you to a solution, using the following steps:

• You specify the goal of the analysis (i.e., find the probability of event A).
• You enter the known probabilities.
• Based on your input, the Calculator selects the right analytical technique and computes the unknown probability.
• The Calculator displays a report, summarizing the research approach and the findings.

The Probability Calculator uses the classic rules of probability - the addition rule, the subtraction rule, the multiplication rule.

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Bayes' Rule Calculator

    The Bayes' Rule Calculator is free. Compute the conditional probability of an event, based on the known probability of other related events. The Bayes' Rule Calculator guides you to a solution, using the following steps:

• You enter the known probabilities.
• Based on your input, the Calculator applies Bayes' Rule and computes the unknown conditional probability.
• The Calculator displays a report, summarizing the research approach and the findings.

Go to Bayes' Rule Calculator

Event Counter

    The Event Counterr is free. Often, to solve a probability or statistics problem, we need to count the number of sample points in a sample space. The event counter addresses this need by:

• Computing factorials.
• Counting the number of event multiples.
• Calculating the number of permutations.
• Calculating the number of combinations.

Event Counter

Random Number Generator

    The random number generator is free. The random number generator uses a computer algorithm to generate (not surprisingly) random numbers. Capabilities include:

• You control the quantity of random numbers (up to 1000) generated in each run.
• You control both the minimum and maximum random numbers generated. For example, you can specify that the random numbers range between 0 and 10, or 1 and 1,000,000, or any other range.
• You control whether the system generates unique random numbers, or whether duplicates are permitted.
• You control whether each run generates a new set of random numbers or repeats a sequence previously generated.

With these features, the Stat Trek random number generator offers convenience and ease of use not found in traditional random number tables.

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Stat Trek Newsletter

    The Stat Trek newsletter is free. With the Stat Trek newsletter at your fingertips, you'll find practical explanations of all things statistical - applications, formulas, and calculations. Get nuts-and-bolts tips in plain English.

• Find the right techniques for valid, effective analysis.
• Identify strengths and weaknesses of your research.
• Conduct cost-effective research.
• Learn about new features, as they are added to the Stat Trek web site.

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