What are the assumptions for independent t test?


  • Independence of the observations. Each subject should belong to only one group.
  • No significant outliers in the two groups.
  • Normality. the data for each group should be approximately normally distributed.
  • Homogeneity of variances. the variance of the outcome variable should be equal in each group.

Which of the following is the most serious violation of an assumption for the t test for independent means?

Which of the following is the MOST serious violation of an assumption for the t test for independent means? the two sample means must be equal. The best way to reduce the variances in the distributions of means when conducting a t test for independent means is to. increase the size of the samples.

When should you use a two sample t test?

The two-sample t-test (Snedecor and Cochran, 1989) is used to determine if two population means are equal. A common application is to test if a new process or treatment is superior to a current process or treatment. There are several variations on this test. The data may either be paired or not paired.

What are the three assumptions for hypothesis testing?

Statistical hypothesis testing requires several assumptions. These assumptions include considerations of the level of measurement of the variable, the method of sampling, the shape of the population distri- bution, and the sample size.

What is the null hypothesis for a 2 sample t-test?

The default null hypothesis for a 2-sample t-test is that the two groups are equal. You can see in the equation that when the two groups are equal, the difference (and the entire ratio) also equals zero.

What is the difference between independent and dependent t test?

The independent samples t-test compares two independent groups of observations or measurements on a single characteristic. The independent samples t-test is the between-subjects analog to the dependent samples t-test, which is used when the study involves a repeated measurement (e.g., pretest vs.

What is the difference between a paired t test and a 2 sample t test?

Two-sample t-test is used when the data of two samples are statistically independent, while the paired t-test is used when data is in the form of matched pairs. To use the two-sample t-test, we need to assume that the data from both samples are normally distributed and they have the same variances.

What is an empirical research report?

Definition of an empirical study: An empirical research article reports the results of a study that uses data derived from actual observation or experimentation. Includes a statement of the hypotheses for the research and a review of other research on the topic.

What are the assumptions of t test?

The common assumptions made when doing a t-test include those regarding the scale of measurement, random sampling, normality of data distribution, adequacy of sample size and equality of variance in standard deviation.

How do you use a t-test to test a hypothesis?

Computing scores for a single-sample test

  1. Take the following input:
  2. Extract the number of samples (n).
  3. Calculate the mean of the sample data.
  4. Calculate the standard deviation (s) of the sample data.
  5. Calculate t and degrees of freedom (df):
  6. Extract probability P from distribution table T by using t and df.

Does data need to be normal for t test?

For a t-test to be valid on a sample of smaller size, the population distribution would have to be approximately normal. The t-test is invalid for small samples from non-normal distributions, but it is valid for large samples from non-normal distributions.

How do you interpret paired t-test results?

Complete the following steps to interpret a paired t-test….

  1. Step 1: Determine a confidence interval for the population mean difference. First, consider the mean difference, and then examine the confidence interval.
  2. Step 2: Determine whether the difference is statistically significant.
  3. Step 3: Check your data for problems.

Should I use a paired or unpaired t-test?

Paired t-tests are considered more powerful than unpaired t-tests because using the same participants or item eliminates variation between the samples that could be caused by anything other than what’s being tested.

What is a two-sample z test used for?

The Two-Sample Z-test is used to compare the means of two samples to see if it is feasible that they come from the same population. The null hypothesis is: the population means are equal.

What are the assumptions of a two sample t test?

Two-sample t-test assumptions

  • Data values must be independent.
  • Data in each group must be obtained via a random sample from the population.
  • Data in each group are normally distributed.
  • Data values are continuous.
  • The variances for the two independent groups are equal.

How do you write an empirical report?

  1. 11 Writing an Empirical Report.
  2. front matter (this may include a confidentiality clause, table of contents, list.
  3. abstract (or ‘executive summary’) [5 per cent]
  4. introduction and literature review (can be separated) [20 per cent]
  5. methodology (and sometimes, procedure) (can include a theoretical model) [10.