# Question: Is There A Significant Difference Between Two Groups?

## How do you know if two averages are statistically different?

When the P-value is less than 0.05 (P<0.05), the conclusion is that the two means are significantly different.

Note that in MedCalc P-values are always two-sided (or two-tailed)..

## How do I compare two groups in SPSS?

Running the ProcedureOpen Compare Means (Analyze > Compare Means > Means).Double-click on variable MileMinDur to move it to the Dependent List area.Click Options to open the Means: Options window, where you can select what statistics you want to see. … Click OK.

## Is t test same as Anova?

The t-test is a method that determines whether two populations are statistically different from each other, whereas ANOVA determines whether three or more populations are statistically different from each other.

## How do you compare two data sets?

Common graphical displays (e.g., dotplots, boxplots, stemplots, bar charts) can be effective tools for comparing data from two or more data sets.

## How do you compare two averages?

How to Compare Two Independent Population AveragesCalculate the sample means. … Find the difference between the two sample means: … Calculate the standard error using the following equation:Divide your result from Step 2 by your result from Step 3. … Look up your test statistic on the standard normal (Z-) distribution (see the below Z-table) and calculate the p-value.More items…

## What is Type I and Type II error in statistics?

In statistical hypothesis testing, a type I error is the rejection of a true null hypothesis (also known as a “false positive” finding or conclusion; example: “an innocent person is convicted”), while a type II error is the non-rejection of a false null hypothesis (also known as a “false negative” finding or conclusion …

## How do you compare two different standard deviations?

Since P was not less than 0.05, you can conclude that there is no significant difference between the two standard deviations. If you want to compare two known variances, first calculate the standard deviations, by taking the square root, and next you can compare the two standard deviations.

## How do I compare two groups in R?

R gives you two standard tests for comparing two groups with numerical data: the t-test with the t. test() function, and the Wilcoxon test with the wilcox. test() function. If you want to use the t.

## Why do we use two sample t test?

The two-sample t-test (also known as the independent samples t-test) is a method used to test whether the unknown population means of two groups are equal or not.

## Why is Anova more powerful than T test?

The t-test compares the means between 2 samples and is simple to conduct, but if there is more than 2 conditions in an experiment a ANOVA is required. … The ANOVA is an important test because it enables us to see for example how effective two different types of treatment are and how durable they are.

## Can Anova be used to compare two groups?

For a comparison of more than two group means the one-way analysis of variance (ANOVA) is the appropriate method instead of the t test. As the ANOVA is based on the same assumption with the t test, the interest of ANOVA is on the locations of the distributions represented by means too.

## How do you know if a two time series is different?

ISSUE: How to compare two time series? VALUE COMPARISON: The values or observed values of the two series may be compared. Two cases may arise: (i) equal length of data, and (ii) unequal length of data. The degree of difference is the number of pair less 1, i.e. df = n – 1.

## How do you compare the means of two groups with different sample sizes?

Most recent answer. One way to compare the two different size data sets is to divide the large set into an N number of equal size sets. The comparison can be based on absolute sum of of difference. THis will measure how many sets from the Nset are in close match with the single 4 sample set.

## Why are unequal sample sizes a problem?

Unequal sample sizes can lead to: … Unequal variances between samples, which affects the assumption of equal variances in tests like ANOVA. Having both unequal sample sizes and variances dramatically affects statistical power and Type I error rates (Rusticus & Lovato, 2014).

## What is the null hypothesis for the test comparing two proportions?

When the null hypothesis states that there is no difference between the two population proportions (i.e., d = P1 – P2 = 0), the null and alternative hypothesis for a two-tailed test are often stated in the following form.

## How do you compare two sets of data in Excel?

Here are the steps to do this:Select the entire data set.Click the Home tab.In the Styles group, click on the ‘Conditional Formatting’ option.Hover the cursor on the Highlight Cell Rules option.Click on Duplicate Values.In the Duplicate Values dialog box, make sure ‘Duplicate’ is selected.Specify the formatting.More items…

## Why is Anova better than multiple t tests?

Two-way anova would be better than multiple t-tests for two reasons: (a) the within-cell variation will likely be smaller in the two-way design (since the t-test ignores the 2nd factor and interaction as sources of variation for the DV); and (b) the two-way design allows for test of interaction of the two factors ( …

## What statistical test should I use to compare two groups?

When comparing more than two sets of numerical data, a multiple group comparison test such as one-way analysis of variance (ANOVA) or Kruskal-Wallis test should be used first.

## Which test to compare two means?

t-testOne of the most common tests in statistics, the t-test, is used to determine whether the means of two groups are equal to each other. The assumption for the test is that both groups are sampled from normal distributions with equal variances.

## What is mean comparison?

The compare means t-test is used to compare the mean of a variable in one group to the mean of the same variable in one, or more, other groups. … We use one-tailed tests to evaluate if the available data provide evidence that the difference in sample means between groups is less than (or greater than ) zero.

## Are two sets of data significantly different?

No. A t-test tells you whether the difference between two sample means is “statistically significant” – not whether the two means are statistically different. A t-score with a p-value larger than 0.05 just states that the difference found is not “statistically significant”.

## What is two proportion test?

Two sample proportion test is used to determine whether the proportions of two groups differ. It calculates the range of values that is likely to include the difference between the population proportions.