Test Statistic And P Value Calculator 476: A legislative committee wants to. Genotype frequencies may be compared using chi square test. Note that the Fisher’s exact test does not have a “test statistic”, but computes the p-value directly. It is defined as the probability of obtaining a result equal to or more "extreme" than the observed one. P-value from Z score. The Simes method for multiple hypothesis testing with positively dependent test statistics. When you are trying to calculate the chi square statistic, you can use our critical value chi square calculator. The F ratio that underlies the analysis of variance test is the square of this, The p-value for the t-test is the probability of recording a t-value as far from zero, and this equals the probability of getting as large an F-ratio as the one evaluated from the data. (Round your test statistics to 2 decimal places and p-values to 4 decimal places. ) 17 minutes ago Confidence Interval Given. The smaller the -value, the stronger the evidence against the null hypothesis. Test workbook (Survival worksheet: Stage Group, Time, Censor). If there is a cell in the table that is used in the calculation of the test statistic that has a count of less than 25, then a modified version of the test is. Correlation and Regression Calculator Find Linear Correlation Coefficient and Regression Line. P-value from t score. Use tables of the t-distribution to compare your value for T to the t n 1+n 2−2 distrib-ution. By then end of this primer you will: Be familiar with how Fisher’s Exact Test is used to determine enrichment; Be aware of the meaning of a p-value arising from Fisher’s Exact Test; II. Or you can find the f value associated with a specified cumulative probability. The stratified test statistic is expressed as (Kalbfleisch and Prentice, 1980): - where the statistics defined above are calculated within strata then summed across strata prior to the generalised inverse and transpose matrix operations. 17) on the standard normal (Z-) distribution — see the above Z-table — and take 1 minus the probability shown. (Use a computer or calculator to find the p-value. The test uses this statistic to calculate the p-value. 857e-08 # To determine the critical value of the test alpha=0. 05 critical alpha level, t(106)=1. 05, x = 56, n = 80. Calculating the P-value in a z test for a. Learn more about different types of probabilities, or explore hundreds of other calculators covering the topics of math, finance, fitness, and health, among others. Calculate Clear. T-Test Calculator for 2 Independent Means T-Test Calculator for 2 Dependent Means T-Test Calculator for a Single Sample. The default alternative hypothesis is the last one listed. Below you can find the study hours of 6 female students and 5 male students. A p-value is the probability that, if the null hypothesis were true, we would observe a statistic at least as extreme as the one observed. The calculator generates solution with detailed explanation. In this case (2 =2. A p-value is the probability that the test statistic would "lean" as much (or more) toward the alternative hypothesis as it does if the real truth is the null hypothesis. If you're interested in using the z statistic for hypothesis testing and the like, then we have a number of other calculators that might help you. In this the test statistic follows a students t-distribution. Upload data for analysis, export results and create reports. A significant p. With the z-test calculator, users can easily calculate z-score from the p-value or the vice versa. n is the sample size The p-value of the test is the area under the normal curve that is in agreement with the alternate hypothesis. , • is the chi-squared distribution with k-1 degrees of freedom • Reject null if p-value < α, for some pre-determined significance level α 2 χk−1 22 p-value =≥Pr(χk−1 X) 9. Call this F obs. This unit will calculate the value of chi-square for a one-dimensional "goodness of fit" test, for up to 8 mutually exclusive categories labeled A through H. 5 if the population mean μ really were 3. Use tables of the t-distribution to compare your value for T to the t n−1 distribution. P Value Calculator Use this calculator to compute a P value from a Z, t, F, r, or chi-square value that you obtain from a program or publication. The hypothesis test is shown. A small p-value. However, we still do not know our t test statistics and whether this statistics is larger than the cut-off value. Graphically, the p value is the area in the tail of a probability distribution. This calculator will tell you the probability value of an F-test, given the F-value, numerator degrees of freedom, and denominator degrees of freedom. The classical model makes some assumptions about the population parameter:. Sample questions A researcher has a less than alternative hypothesis and wants to run a single sample […]. This should be self-explanatory, but just in case it's not: your t-score goes in the T Score box, you stick your degrees of freedom in the DF box (N - 1 for single sample and dependent pairs, (N 1 - 1) + (N 2 - 1) for independent samples), select your significance level and whether you're testing a one or two-tailed hypothesis (if you're not sure, go with the. P-value from F-ratio score. In summary, to perform a hypothesis test we must first choose a statistic of interest and null hypothesis for the true underlying parameter (population value) for that statistic. Related Resources. 60 versus H1: p >. sx is the sample standard deviation, if you know the population standard deviation, σ , then replace sx with σ in the equation for the test statistic. Once you have entered your data, click on the Calculate button and expect to see output in the beige cells (they should be white if you are using older versions of Netscape). $\begingroup$ For a two tailed test, you're looking for the probability that the value is less than -11. For a one-sample z-test with known population mean and standard deviation, the sample size n = 1. 408, and the p-value of this hypothesis test is the probability of obtaining a test statistic value z which represents a larger distance below the hypothesized proportion than the observed z = – 1. Every test statistic has a corresponding probability or p-value. A simple online T Test Critical Value calculator to calculate the critical values from the one and two tailed probabilities and the degrees of freedom. Chi Square P-Values. 1 and df=1:. When the calculated value of the test statistic from the sample is negative, calculate a lower-tailed p-value and in step 5 enter K2 in Optional storage. One can select a power and determine an appropriate sample size beforehand or do power analysis afterwards. Hypothesis tests or test of significance involve the calculation of a number known as a p-value. Computes p-values and F values for the Fisher-Snedecor distribution. If there is a cell in the table that is used in the calculation of the test statistic that has a count of less than 25, then a modified version of the test is. The results generated by the calculator include the t-statistic, the degrees of freedom, the critical t-values for both one-tailed (directional) and two-tailed (non-directional) hypotheses, and the one-tailed and two-tailed probability. Following is an excerpt from a journal: n Allele frequency + – P value. StatCrunch provides data analysis via the Web. probability P (A | B) = ( ) ( ) P B P A B P (x) Probability of x Probability of x P (x) = Total no of outcomes No of favorable outcomes. Interpreting test statistics, p-values, and significance Analysis Test statistic Null hypothesis Alternative hypothesis Results p-value significance decision Difference-of- means test t (two-tailed) (see note 1) 1 = 2 1 ≠ 2 big t (> +2. Fill the P-values into the table below. , the area under the chi-square distribution from the chi-square value to positive infinity), given the chi-square value and the degrees of freedom. In connection with the t distribution calculator, a cumulative probability refers to the probability that a t statistic or a sample mean will be less than or equal to a specified value. The calculated t-statistic and p-value match what we expect from the SciPy library implementation. Calculate a p value and compare it to a significance level (a) or confidence level (1-a) Interpret the results to determine if you can accept or reject the null hypothesis. The steps to perform a test of proportion using the critical value approval are as follows: State the null hypothesis H 0 and the alternative hypothesis H A. [Although the Fisher test is traditionally used with relatively small samples, the programming for this page will handle fairly large samples, up to about n=1000, depending on how the frequencies are arrayed within the four cells. You can use test statistics to determine whether to reject the null hypothesis. We can say this is approximately 0. In statistical data analysis, it is also called standard score, z value, standardized score and normal score. 002 and that is less than 0. Warning: The P-value may be given in scienti c notation. The t-statistic was not significant at the. In order to perform a t-test, one first has to calculate the "degrees of freedom. Skip navigation Sign in. Now add (sum) the last column. For an upper-tailed test, you need to subtract this probability from 1. Once the value of dollar cash flows is known, the actual period cash flows are multiplied by the annuity factor to find out the present value of the annuity. Journal of the American Statistical Association, 92, 1601–1608. Test Considerations. Fisher, a leading statistician of the first half of the twentieth century. When you run a hypothesis test, you compare the p value from your test to the alpha level you selected when you ran the test. p-Value Calculator for a Chi-Square Test. of rejecting the hypothesis under consideration. This would imply that if a sample K-S statistic is < the critical D value at say the. It does not give you the critical value. If a population parameter is hypothesized to be greater than or less than some value, a one-tailed test is used. Subtracting P from one: gives Q, the probability that the observed z score is due to chance. A small $$p$$-value is an indication that the null hypothesis is false. Calculates exact P value and 95% confidence interval. Chi-square: Testing for goodness of t 4{5 Generally speaking, we should be pleased to nd a sample value of ˜2= that is near 1, its mean value for a good t. So if the p-value is less than the significance level (usually. Our chi square calculator, commonly used in statistics and probability calculations, can help you solve for probability (P value) or the significance of a chi-square (X 2) test, based upon the known values for X 2 and degrees of freedom (df) or solve for X 2 based upon the known values from the probability and degrees of freedom. One Sample t-Test in Excel QI Macros Add-in Conducts t Tests and Interprets Results. If this probability is \very low", we might think the hypothesized value pis incorrect. How to do simple t-tests These are statistical tests that will tell you if there is a significant difference between two sets of data, or if the average of a set of data differs significantly from a predicted value. Using the same data I perform a correlation test and a regression, the P value for the correlation can take values bellow 0. Calculate the t-statistic, which is given by T = d¯ SE(d¯). For this type of test, the ratio is: Variance explained by your model / Variance explained by the intercept-only model. Below is an online calculator of the Mann-Whitney U test. It is usually the last value in the output. The F ratio that underlies the analysis of variance test is the square of this, The p-value for the t-test is the probability of recording a t-value as far from zero, and this equals the probability of getting as large an F-ratio as the one evaluated from the data. This calculator will tell you the one-tailed (right-tail) probability value for a chi-square test (i. The p-value for the is the probability that the test statistic would be at least as extreme as we observed, if the null hypothesis is true. Calculate two tailed and one tailed p values with the given t test and degree of freedom using Probability (P) Value T test Calculator. The test statistic follows the standard normal distribution (with mean = 0 and standard deviation = 1). Since the test statistic is a z-score, use the Normal Distribution Calculator to assess the probability associated with the z-score. Compute the $$p$$-value of the test. P value which is greater than the level of significance indicates that we fail to reject the null hypothesis. The probability can be calculated from the cumulative standard normal distribution: Which gives the probability P that an experimental result with a z value less than or equal to that observed is due to chance. Print out the value of the test statistic; Visualize the distribution. If you're interested in using the t statistic for hypothesis testing and the like, then we have a number of other calculators that might help you. This is the same hypothesis tested by the t Stat for the beta. 10, which means that there is a 10% probability that any deviation from expected results is due to chance only. P- value = Valor P Conclusion = Conclusión. Call this F obs. This is the probability that we'll find the same test statistic or more extreme value assuming that the null hypothesis is true. Or you can find the f value associated with a specified cumulative probability. • Calculate the expected values • Use the observed and expected values to calculate the chi-square test statistic • Establish the significance level you need (usually 95% p = 0. The value of the power. sx is the sample standard deviation, if you know the population standard deviation, σ , then replace sx with σ in the equation for the test statistic. at least as small as that provided by the sample b. t e is an important part of t-test to check if the results of statistical experiment is statistically significant. The F-value is the test statistic used to determine whether the model is missing higher-order terms that include the predictors in the current model. One of these tests is used for the comparison of two means, which is commonly applied to many cases. Alpha levels can also be written as percentages. The Null Hypothesis, is usually that the observations are the result of chance. 83) in my TI83 and i got. This calculator will generate a step by step explanation on how to apply t - test. Because of the central limit theorem, many test statistics are approximately normally distributed for large samples. 0) small p (< 0. This online calculator calculates z score from p value. RT(x,), then F. So how do we calculate the probability below a negative z-value (as illustrated below)?. This article describes the formula syntax and usage of the F. When you run a hypothesis test, you compare the p value from your test to the alpha level you selected when you ran the test. 02 approximately, the T distribution is symmetric, this is going to be approximately 0. T-Test Statistic. Since the calculated value of the test statistic from the sample is positive, calculate an upper-tailed p-value. Referring to the contingency table below, the Null Hypothesis for the McNemar test is that the marginal probability of Test 1 being positive is equal to the marginal probability of Test 2 being positive as well. The value returned by T. These tests arise in many statistical procedures. Please input numbers in the required fields and click CALCULATE. 17) on the standard normal (Z-) distribution — see the above Z-table — and take 1 minus the probability shown. Shapiro-Wilk Test Calculator The maximum sample size is 5000 tails: right for Shapiro-Wilk Test you can use only right tail i When Shapiro-Wilk Test, the w statistic is only positive and represent the difference between the Normal Distribution and the observations. A Single Sample Confidence Interval Calculator (T Statistic) A Single. Hence, in this Python Statistics tutorial, we discussed the p-value, T-test, correlation, and KS test with Python. The steps to perform a test of proportion using the critical value approval are as follows: State the null hypothesis H 0 and the alternative hypothesis H A. A low p-value is a stronger signal for a discrepancy and conventionally values under 0. Therefore, the smaller the p-value, the more important ("significant") your results. In case you don't know, the chi square statistic is used to compare two categorical variables to determine if they are related. For example, if I desired an 80% probability of detecting an effect that I expect will be equivalent to r =. Calculate the mean, standard deviation, and n in To find the p-value. Statistics calculator to calculate basic descriptive statistics including minimum, maximum, sum, count, mean, median, mode, standard deviation and variance. 95) The problem is, the table runs out of values at 3. An example. net : medcalc. 05) and the number of degrees of freedom • Compare the chi-square statistic with the critical value from the table • Make a decision about your hypothesis. This is the χ 2 test statistic. Calculate the p-value. While some posts in our Minitab blog focus on understanding t-tests and t-distributions this post will focus more simply on how to hand-calculate the t-value for a one-sample t-test (and how to replicate the p-value that Minitab gives us). 488 p Value: 0. Run a T-test on this list of numbers to test the hypothesis that m=54. The calculator will find the p-value for two-tailed, right-tailed and left-tailed tests from normal, Student's (T-distribution), chi-squared and Fisher (F-distribution) distributions. This is done only when the null hypothesis is supported. StatCrunch provides data analysis via the Web. Enter the sample mean, population mean, sample standard deviation, population size and the significance level to know the T score test value, P value and result of hypothesis. Powerful p-value calculator online: calculate statistical significance using a Z-test or T-test statistic. A second method of presenting method of presenting the results of a statistical test reports the extent to which the test statistic disagrees with the null hypothesis and leaves to the reader the task of deciding whether to reject the null hypothesis. Suppose the z score (the observed value of Z) is x. The calculator uses the probabilities from the student t distribution. Computing P-values for the Sign Test. By then end of this primer you will: Be familiar with how Fisher’s Exact Test is used to determine enrichment; Be aware of the meaning of a p-value arising from Fisher’s Exact Test; II. 9909 and the p-value = 0. Let’s find the critical value of the test. Depending on its realized value s ( x  , x  , … , x [ m ] ), we will reject or not reject. The two-tailed test is used when the null hypothesis can be rejected regardless of the direction of the effect. However, once you calculate the test statistic, Excel can get the critical values and the P-values needed to complete the test. Instructions: This calculator conducts a t-test for two paired samples. If you want to calculate the test statistic based on unpaired data samples, see our Unpaired t-test Calculator. Confidence levels computed provide the probability that a difference at least as large as noted would have occurred by chance if the two population proportions were in fact equal. Calculate the test statistic and p-value for each sample. 05 (differences range from 0. Probability & Statistic Unit Test Directions: You may use a calculator to complete the test, but be sure to show all your work when necessary. TEST function: • Array: the range of the sample data. Generate a large number P rep of permutations where observations are permuted within each block. 05) yes (significant difference of means) reject Ho, accept Ha small t (< +2. However: * For some test statistics you will need a bit more information to calculate the p-value, for example the number of degrees of freedom. What this fails to tell us is the magnitude of the difference. The interpretation of the t-test statistic with the critical value, and the p-value with the significance level both find a significant result, rejecting the null hypothesis that the means are equal. 05, we reject the null hypothesis and conclude that the mean is not 88. 1 or 2 Tailed Test. Determine the critical value, χ20, and the rejection region. The value of the power. The outcomes generated by our calculator consist of the p-value from each test and the test statistic (e. falls in the critical region C of the test, i. However, once you calculate the test statistic, Excel can get the critical values and the P-values needed to complete the test. Suppose the z score (the observed value of Z) is x. 02 approximately, the T distribution is symmetric, this is going to be approximately 0. Calculating the P-value in a z test for a. Print out the value of the test statistic; Visualize the distribution. Partial credit is possible, and points are list in parentheses. Student t-values for both one-tailed (right-tail) and two-tailed probabilities will be returned. How to Calculate P Value. Calculates z, t, F, or chi-square from a probability. Factor analysis is an interdependence technique. (Give your answer correct to four decimal places. 0054, the dfs are approximately 18. p-value = 1 - TDIST(1. A TI-83 calculator can help you calculate p-values using multiple tests. Powerful p-value calculator online: calculate statistical significance using a Z-test or T-test statistic. For one-sample t tests, we will round the t-test statistic to 4 decimal places and the P-value to 3 significant figures. Finding a Central Value; Calculate the Mean Value and The Mean Machine; Find the Median Value; Find the Mode or Modal Value; Activity: Averages Brain-Teaser; Advanced: Calculate the Mean from a Frequency Table; Weighted Mean; Geometric Mean; Harmonic Mean. How can I calculate in Mathematica the probability of a condition concerning ranked values from the same distribution? For instance: Pr[x1 - x2 < 1 | {x1, x2} ~ N(0,1)], where x1 is the second. P Value from Chi-Square Calculator. Hence, in this Python Statistics tutorial, we discussed the p-value, T-test, correlation, and KS test with Python. T-Test Calculator for 2 Independent Means T-Test Calculator for 2 Dependent Means T-Test Calculator for a Single Sample. Clear results with links to extensive explanations. Using a simple formula, you can easily determine the p-value for your tests and thereby conclude strong or weak support of the null hypothesis. Ranks go from 1 to N, where N is the sum of sizes and. 2307/2532694. If The Absolute Value Of The Calculated Test Statistic For A Hypothesis Is Greater Than The Critical Value Of The Test Statistic (taken From The Statistical Table), Then: A) Do Not Reject The Null Hypothesis B) Reject The Null Hypothesis 2. To calculate a p-value we use the appropriate software or statistical table that corresponds with our test. This calculator is designed to generate a p-value from a chi-square score. P-value from F-ratio score. Please enter the necessary parameter values, and then click 'Calculate'. Calculate two tailed and one tailed p values with the given t test and degree of freedom using Probability (P) Value T test Calculator. The P-value is the probability of observing a sample statistic as extreme as the test statistic. Demonstrates the basics of hypothesis testing using the P-value method: find the test statistic which in turn gives us the P-value, then compare the P-value to the level of significance (alpha) to. Critical values* of the Rayleigh test of uniformity with the test-statistics n a 0. Recalling the Significance Testing review, we would calculate standard deviation and evaluate the results using a t-test. Otherwise, it gives you the probability of the value being less than the first parameter. 483 Critical Chi-Square Value: 9. Using the same data I perform a correlation test and a regression, the P value for the correlation can take values bellow 0. Joiner, Statistics Department, The Pennsylvania State University 1976 Acknowledgments: Helpful assistance from Dr. The structure stats includes only the value of the rank sum test statistic. 05 are considered strong evidence for departure from normality (or IID, for some tests). Since the calculated value of the test statistic from the sample is positive, calculate an upper-tailed p-value. What's Cool about QI Macros F-Test? Interprets the Results for You: QI Macros compares the p value to alpha and tells you what that means. In the nal analysis, we must be guided by our own intuition and judgment. $\begingroup$ Are you familiar with the definition of a p-value? [If not, see the first sentence here. Given sample results and the test statistic, practice calculating the P-value in a one-sample z test for a proportion. Calculate Test Statistic. (Give your answer correct to two decimal. 45954929 and a P Value of. Calculate a fractional degrees of freedom as given below, or use the smaller of n 1-1 or n 2. at least as small as that provided by the sample b. •Find the strength of evidence by P-value : from a future set of data, compute the probability that the summary testing statistics will be as large. We use MathJax. The P-value for conducting the left-tailed test H 0: μ = 3 versus H A: μ < 3 is the probability that we would observe a test statistic less than t* = -2. Critical Values Calculator. When the test statistic is less than or equal to zero, PROC FREQ computes the left-sided p -value, which is the probability of a smaller value of the statistic occurring under the null hypothesis. On Statistical Hypothesis Testing via Simulation Method two moments of the test's statistic. Repeat assuming the same value of x but with n = 29. It can also run the five basic Statistical Tests. You should also consider the p value. The formula for the calculation of the p-value can be derived by using the following steps: Calculating P-Value from a Z Statistic. This calculator will tell you the one-tailed and two-tailed probability values of a t-test, given the t-value and the degrees of freedom. The type of testing varies according to the level of measurement of the variables involved. TI-83 Graphing Calculator Manual for Moore and McCabe's Introduction to the Practice of Statistics. by "International Journal of Business, Accounting and Finance (IJBAF)"; Business, international Financial statements Economic aspects. If you need to derive a chi-square score from raw data, you should use our chi-square calculator (which will additionally calculate the p-value for you). Probability & Statistics; Sample size calculator calculates the sample size in order to design statistics data research experiments. Therefore, we fail to reject the null hypothesis and conclude that the difference was not significant. n1 = 50 n2 = 6 x1 = 31 x2 = 29 s1 = 1. Using a simple formula, you can easily determine the p-value for your tests and thereby conclude strong or weak support of the null hypothesis. This unit will calculate the value of chi-square for a one-dimensional "goodness of fit" test, for up to 8 mutually exclusive categories labeled A through H. A standardized test is scored in a standard manner. The first approach of hypothesis testing is a classical test statistic approach, which computes a test statistic from the empirical data and then makes a comparison with the critical value. For example, a p value of 5% is 0. Once the value of dollar cash flows is known, the actual period cash flows are multiplied by the annuity factor to find out the present value of the annuity. 83 right? so i just did invNorm(0. com · share on facebook · tweet. Calculate the p-value for The test's statistic value. Please enter the necessary parameter values, and then click 'Calculate'. Outputs Χ 2 and p-value. Explanation This form does a G-test calculation to determine the outcome of an A/B test. Don't report a P-value as 0 if you can get a more accurate value in. These tests arise in many statistical procedures. I have some t-values and degrees of freedom and want to find the p-values from them (it's two-tailed). The calculated t-statistic and p-value match what we expect from the SciPy library implementation. When you run a hypothesis test, you compare the p value from your test to the alpha level you selected when you ran the test. The t distribution (2) In the last exercise we calculated the critical value using the qt() function. Use the applet to calculate the P-value for your final test of significance, considering the possibilities that your sample mean comes out to 12, 13, or 14, and considering the two possible alternative hypotheses µ < 15 and µ ≠ 15. The normal probability plot is. at least as small as that provided by the population d. You can use this T-Value Calculator to calculate the Student's t-value based on the significance level and the degrees of freedom in the standard deviation. If you're interested in using the z statistic for hypothesis testing and the like, then we have a number of other calculators that might help you. A significant p. P-value formula, Z-score formula, T-statistic formula and explanation of the inference procedure. Fore more information on 2-Sample t-tests View the Comparing Two Means: 2 Sample t-test tutorial. Using Excel, Chapter 8: Hypothesis Testing - One Sample Excel alone does not conduct complete hypothesis tests1. We can say this is approximately 0. Finding P-values TI-84 Instructions Rick Gumina Page 1 of 1 Finding P-values_calculator-TI84. From the sample statistics, find the value of p-bar used to test the hypothesis that the population proportions are equal. (Round the test statistic to two decimal places. Below is how to go about it: For the sake of verification, I first calculate p for a given chi-square value = 1. The calculator will find the p-value for two-tailed, right-tailed and left-tailed tests from normal, Student's (T-distribution), chi-squared and Fisher (F-distribution) distributions. Step 1: We need to find out the test statistic z. This online calculator calculates z score from p value. Simply enter your t statistic (we have a t score calculator if you need to solve for the t score) and hit calculate. How to Calculate P Value. 4721 and the p-value is 0. Probability and Statistics Measures of Central Value. If the test statistic is greater than the upper-tail critical value or less than the lower-tail critical value, we reject the null hypothesis. The final section of the output gives the value of the chi-squared test in the first row. For example, if I desired an 80% probability of detecting an effect that I expect will be equivalent to r =. WEIBULL: Returns the values of the Weibull distribution. p Use a calculator or a formula to find this. We can say this is approximately 0. The p-value is the probability of rejecting the null hypothesis, that the variables are independent, when it is in fact true. value: the p-value for the test. and then to calculate the value of the test statistic. 05), the null hypothesis is rejected and at least one significant difference can be assumed. 841459 Conclusion: Since the results give you a test statistic, χ C or McNemar’s chi-squared value, equal to 30. To find the p-value, calculate P(χ 2 > 3). Hypothesis tests or test of significance involve the calculation of a number known as a p-value. p Use a calculator or a formula to find this. ? An environmental agency claimed more than 33% of consumers have stopped buying a certain product because of environmental concerns. 05, we reject the null hypothesis and conclude that the mean is not 88. Practical Meta-Analysis Effect Size Calculator David B. by Marco Taboga, PhD. More specifically, the p-value of a statistical significance test represents the probability of obtaining values of the test statistic that are equal to or greater in magnitude than the observed test statistic. And if you calculate this, this should give us approximately 1. The test statistic value is very important because we can then take this test statistic value and look up the p-value on a table or use a p-value calculator to find the p-value. It is usually the last value in the output. Use tables of the t-distribution to compare your value for T to the t n 1+n 2−2 distrib-ution. Calculate two tailed and one tailed p values with the given t test and degree of freedom using Probability (P) Value T test Calculator. 99, as you probably know. Each of the links in white text in the panel on the left will show an annotated list of the statistical procedures available under that rubric.