Confidence interval for a proportion. Just enter the inputs of two samples in the above T statistic calculator for two Samples and click calculate to get the result. To compare the difference between two means, two averages, two proportions or two counted numbers. Standard Deviation and Mean. The means are from two independent sample or from two groups in the same sample. Two Independent Samples with data Calculator. Use the Standard Deviation Calculator to calculate your sample's standard deviation and mean. Sample Size Calculator Terms: Confidence Interval & Confidence Level. This project was supported by the National Center for Advancing Translational Sciences, National Institutes of Health, through UCSF-CTSI Grant Numbers UL1 TR000004 and UL1 TR001872. This calculator uses JavaScript functions based on code developed by John C. Pezzullo. A number of additional statistics for comparing two groups are further presented. The formula to calculate the confidence interval is: Confidence ... where: p 1, p 2: sample 1 proportion, sample 2 proportion; z: the z-critical value based on the confidence level; n 1, n 2: sample 1 size, sample 2 size; To find a confidence interval for a difference between two population proportions, simply fill in the boxes below and then click the “Calculate” button. Confidence Interval for Two Independent Samples, Continuous Outcome There are many situations where it is of interest to compare two groups with respect to their mean scores on a continuous outcome. Enter how many in the sample, the mean and standard deviation, choose a confidence level, and the calculation is done live. Including number needed to treat (NNT), confidence intervals, chi-square analysis. Two-sample t-test free online statistical calculator. Read Confidence Intervals to learn more. A significance value (P-value) and 95% Confidence Interval (CI) of the difference is reported. For example, we might be interested in comparing mean systolic blood pressure in men and women, or perhaps compare body mass index (BMI) in smokers and non-smokers. There are different equations that can be used to calculate confidence intervals depending on factors such as whether the standard deviation is known or smaller samples (n. 30) are involved, among others. The above method calculates the difference between the observed means in two independent samples. The confidence interval (also called margin of error) is the plus-or-minus figure usually reported in newspaper or television opinion poll results. Then enter the tail type and the confidence level and hit Calculate and the test statistic, t, the p-value, p, the confidence interval's lower … Type in the values from the two data sets separated by commas, for example, 2,4,5,8,11,2. T-test online. Confidence Interval Calculator.