# Statistical Calculator ## Related Calculators

Wikipedia has good articles on statistics. Sample size is the number of completed responses your survey receives.

In the equation above, i is the index that refers to the location of a value in a set, x i is an individual value, and N is the total number of values. What is the population size? Once an interval is calculated, it either contains or does not contain the population parameter of interest. For each question, what do you expect the results will be? Essentially, sample sizes are used to represent parts of a population chosen for any given survey or experiment. What confidence level do you need?

Statistical power is essentially a measure of whether your test has adequate data to reach a conclusive result. This calculator computes the minimum number of necessary samples to meet the desired statistical constraints. Learn more Where is statistical power in your sample size calculator? Refer to the root calculator if necessary for a review of n th roots.

The equation for calculating sample size is shown below. Want to know how to calculate it? Survey sampling can still give you valuable answers without having a sample size that represents the general population. It is important to note that the equation needs to be adjusted when considering a finite population, as shown above. In many cases, if Optimizely detects an effect larger than the one you are looking for, you will be able to end your test early.

The value returned by the calculator is the effect size attributable to the addition of set B to the model. Use our online probability calculator to find the single and multiple event probability with the single click. Make use of probability calculators to solve the probability problems with ease. Use this online probability calculator to calculate the single and multiple event probability based on number of possible outcomes and events occurred.

## All statistics calculators We will be in touch shortly. The confidence level is the amount of uncertainty you can tolerate. These free statistics calculators are offered humbly in the hope that they will contribute in some small way to the advancement of science and the betterment of humanity. The minimum relative change in conversion rate you would like to be able to detect. It can be calculated by dividing the number of possible occurrence by the total number of options.

Click here to receive the latest news, product updates, event announcements, and other communications from Optimizely and our subsidiaries. The confidence level is a measure of certainty regarding how accurately a sample reflects the population being studied within a chosen confidence interval. Probability is about finding the likelihood of some events to happen. Simple Probability Calculator. Our sample size calculator makes it easy.

You also agree to receive news, product updates, event announcements, and other communications from Optimizely and our subsidiaries. The probability that your sample accurately reflects the attitudes of your population. The geometric mean in mathematics is a type of average that uses the product of the values in a set to indicate central tendency.

How many people are there to choose your random sample from? The sample size calculator computes the critical value for the normal distribution. This is in contrast to the arithmetic mean that performs the same function using the sum of the values in the set rather than their products.

It can refer to an existing group of objects, systems, or even a hypothetical group of objects. With millions of qualified respondents, SurveyMonkey Audience makes it easy to get survey responses from people around the world instantly, from almost anyone. For an explanation of why the sample estimate is normally distributed, study the Central Limit Theorem. How do I determine the baseline conversion rate?

Any feedback, positive or negative, is important. Simply ensure that the correct standard deviation is being used s vs. The higher the probability of an event, the more certain that the event will occur. Calculators and Converters. The best example of probability would be tossing a coin, where the probability of resulting in head is.  Rollouts is a Free Access Subscription under our Terms. The total number of people in the group you are trying to study. In the meantime, check out our resources to start planning your optimization program. If the sample size calculator says you need more respondents, we can help. Unlike the arithmetic mean, any given percentage change in the geometric mean has the same effect on the geometric mean.

Why is your calculator different from other sample size calculators? Analyzing Survey Data Google Forms vs. It is based on the formula used in Optimizely's Stats Engine. When combined, these two techniques mean you no longer need to wait for a pre-set sample size to ensure the validity of your results.