when are equal variances not assumed ?

Description

https://libguides.library.kent.edu/SPSS/IndependentTTest

https://libguides.library.kent.edu/SPSS/IndependentTTest
SPSS Tutorials: Independent Samples t Test – Kent State University
5 days agoThe output in the Independent Samples Test table includes two rows: Equal variances assumed and Equal variances not assumed. If Levene’s test indicates that the variances are equal across the two groups (i.e., p -value large), you will rely on the first row of output, Equal variances , when you look at the results for the actual …
Paired Samples T Test
The Paired Samples t Test compares the means of two measurements taken from the same individual, object, or related units. These paired measurements can represent things like: A measurement taken at two different times (e.g., pre-test and post-test score with an intervention administered between the two time points)
One-Way Anova
3 Equal Variances Not Assumed: Multiple comparisons options that do not assume equal variances. For detailed information about the specific comparison methods, click the Help button in this window. 4 Significance level: The desired cutoff for statistical significance. By default, significance is set to 0.05.
One Sample T Test
The One Sample t Test examines whether the mean of a population is statistically different from a known or hypothesized value. The One Sample t Test is a parametric test.. This test is also known as: Single Sample t Test; The variable used in this test is known as: Test variable; In a One Sample t Test, the test variable’s mean is compared against a test value, which is a known or …
Chi-Square Test of Independence
Notice how within each smoking category, the heights of the bars (i.e., the number of males and females) are very similar. That is, there are an approximately equal number of male and female nonsmokers; approximately equal number of male and female past smokers; approximately equal number of male and female current smokers.
Data – Spss Format (*.Sav)
Data – Spss Format (*.Sav) – SPSS Tutorials: Independent Samples t Test – Kent State University
Frequency Tables
C Charts: Opens the Frequencies: Charts window, which contains various graphical options. Options include bar charts, pie charts, and histograms. For categorical variables, bar charts and pie charts are appropriate. Histograms should only be used for continuous variables; they should not be used for ordinal variables, and should never be used with nominal variables.

https://www.statology.org/equal-variance-assumption

https://www.statology.org/equal-variance-assumption
What is the Assumption of Equal Variance in Statistics? – Statology
April 11, 2021 by Zach What is the Assumption of Equal Variance in Statistics? Many statistical tests make the assumption of equal variance. If this assumption is violated, then the results of the tests become unreliable. The most common statistical tests and procedures that make this assumption of include: 1. ANOVA 2. t-tests 3.

https://www.statology.org / determine-equal-or-unequal-variance

https://www.statology.org / determine-equal-or-unequal-variance
How to Determine Equal or Unequal Variance in t-tests – Statology
1. Use the Variance Rule of Thumb. As a rule of thumb, if the ratio of the larger variance to the smaller variance is less than 4 then we can assume the variances are approximately equal and use the Student’s t-test. For example, suppose we have the following two samples: Sample 1 has a variance of 24.86 and sample 2 has a of 15.76.

https://usq.pressbooks.pub/statisticsforresearchstudents/chapter/independent-t-test-assumptions

https://usq.pressbooks.pub/statisticsforresearchstudents/chapter/independent-t-test-assumptions
Section 3.3: Independent T-test Assumptions, Interpretation, and Write …
Red: Test statistics Blue: Means and standard deviations Green: The first thing you should examine is Levene’s test. If this test is nonsignificant, that means you have homogeneity of variance between the two groups on the dependent or outcome variable.

https://stats.stackexchange.com/questions/116511/explanation-for-non-integer-degrees-of-freedom-in-t-test-with-unequal-variances

https://stats.stackexchange.com/questions/116511/explanation-for-non-integer-degrees-of-freedom-in-t-test-with-unequal-variances
Explanation for non-integer degrees of freedom in t test with unequal …
The SPSS t-Test procedure reports 2 analyses when comparing 2 independent means, one analysis with equal variances assumed and one with equal variances not assumed. The degrees of freedom (df) when Stack Exchange Network

https://stats.stackexchange.com/questions/305/when-conducting-a-t-test-why-would-one-prefer-to-assume-or-test-for-equal-vari

https://stats.stackexchange.com/questions/305/when-conducting-a-t-test-why-would-one-prefer-to-assume-or-test-for-equal-vari
When conducting a t-test why would one prefer to assume (or test for …
They argue, based on extensive simulations from distributions either meeting or not meeting the assumptions imposed by a t-test, (normality and homogenity of variance) that the welch-tests performs equally well when the assumptions are met (i.e., basically same probability of committing alpha and beta errors) but outperforms the t-test if the …

https://www.statisticshowto.com/levene-test

https://www.statisticshowto.com/levene-test
Levene Test for Equality of Variances – Statistics How To
If the p-value is larger than the alpha level, then you can say that the null hypothesis stands — that the variances are equal; if the p-value is smaller than the alpha level, then the implication is that the variances are un equal. Run a Levene’s Test for Equality of Variances in SPSS

https://statkat.com/stat-tests/two-sample-t-test-equal-variances-not-assumed.php

https://statkat.com/stat-tests/two-sample-t-test-equal-variances-not-assumed.php
Two sample t test – equal variances not assumed – Statkat
When to use? Deciding which statistical method to use to analyze your data can be a challenging task. Whether a statistical method is appropriate for your data is partly determined by the measurement level of your variables. The two sample t t test – equal variances not assumed requires the following variable types:

https://statistics.laerd.com/statistical-guides/independent-t-test-statistical-guide.php

https://statistics.laerd.com/statistical-guides/independent-t-test-statistical-guide.php
Independent t-test for two samples – Laerd
The effect of not being able to assume equal variances is evident in the final column of the above figure where we see a reduction in the value of the t-statistic and a large reduction in the degrees of freedom (df). This has the effect of increasing the p-value above the critical significance level of 0.05. In this case, we therefore do not …

https://stats.libretexts.org/Bookshelves/Applied_Statistics/Natural_Resources_Biometrics_(Kiernan)/04:_Inferences_about_the_Differences_of_Two_Populations/4.02:_Pooled_Two-sampled_t-test_(Assuming_Equal_Variances)

https://stats.libretexts.org/Bookshelves/Applied_Statistics/Natural_Resources_Biometrics_(Kiernan)/04:_Inferences_about_the_Differences_of_Two_Populations/4.02:_Pooled_Two-sampled_t-test_(Assuming_Equal_Variances)
4.2: Pooled Two-sampled t-test (Assuming Equal Variances)
Oct 6, 2023Welch’s t-test statistic does not assume that the population variances are equal and can be used whether the population variances are equal or not. … Two-Sample Assuming Equal Variances : Variable 1. Variable 2. Mean. 3.785714. 6.228571. Variance. 0.224762. 0.875714. Observations. 7. 7. Pooled . 0.550238 : Hypothesized Mean … lesoutrali bot