Parametric vs nonparametric tests

Whether a test is parametric or nonparametric depends on whether the data set assumes a normal distribution or not. If the data was drawn from a population that is normally distributed, then the subsequent test is known as a subsequent test. However, if the data comes from a non-normal distribution, then the tests conducted are nonparametric. Parametric tests are more common and statistical since some assumptions can be made about the parameters. If this is not possible, then one uses nonparametric tests.

Advantages of parametric tests

  1. They produce trustworthy results even for non-normal distributions
  2. For these results to be reliable even when the continuous data is skewed and not normally distributed, some conditions must be met. In the 1-sample t-test, the sample size should be greater than 20 while in the 2-sample t-test it should exceed 15 observations in each group. One-way ANOVA requires 15 observations for each group if the groups range from 2-9. If the groups are in the range of 10-12, each group requires at least 20 observations for the one-way ANOVA. The central limit theorem makes it possible to conduct non-normally distributed data using parametric tests

    Reliable results can be obtained from data even if it differs in variability unlike in nonparametric tests Parametric tests have more statistical power and they can easily identify an underlying effect

Advantages of nonparametric tests

    They can be better in some fields of study because they use the median as opposed to the mean used in parametric tests. They can be used for non-normally distributed data even with a small sample size These tests can analyze ordinal, and ranked data and outliers

Parametric and nonparametric tests for comparing two or more groups

It is essential to consider whether the mean or median is the perfect estimate for the sample at hand. The following tests are the equivalents of parametric and nonparametric tests but proper consideration should be made first. Statisticians tend to use parametric tests because they are a stronger statistical tool.

Parametric test Nonparametric equivalent
Paired t-test Wilcoxon rank sum test
Unpaired t-test Mann-Whitney U test
Pearson correlation Spearman correlation
One-way ANOVA Kruskal Wallis test, Mood’s median test

Differences between parametric and nonparametric tests

Parametric test Nonparametric equivalent
Rely on normal distribution Rely on any distribution, even non-normal
Use the mean Use median
Require large sample size Can be used even for small samples
More statistical power Less chances of detecting effects

Before settling on a test, one should consider if there exists a hypothesis or not, and the type of data under observation. If the mean is an ideal estimate and you have a small sample size, consider increasing it where possible. However, if the sample is small and the median is the most suitable measure, then proceed with it despite the lower statistical power.

All You Need To Do

Fill in order details

Place your order by giving us instructions and requirements, provide deadline, and make the payment.

We work on your paper

Our customer service team will assign the writer/team of witers that best fits your writing criteria to work on your paper.

Rate and download

Download your paper after our quality assurance team proofreads, edits, and scans for plagiarism. This guarantees a quality paper.

We always stay with our clients.

98% of our clients are satisfied with the work of our customer support. We respond to any issue within the shortest time possible - Your happiness is our aim

Our Client Say

Clients Testimonials

Do you have any question?


The process of placing an order or an inquiry is user initiated. You can choose to place an order via our order form or place an inquiry. Once the order is placed, the support team chooses the best skilled expert to handle your task. The writer is paid after successful and timely delivery of the work
Yes. The cover and reference pages are free of charge. Revisions are also free. A revsion maybe chargable of it entails change of initial instructions.
Yes. We complete online tests with the highest level of privacy, confidentiality and integrity
Our payment system accept all credit cards and PayPal as avenue of payments.
Contact support via live chat, email at [email protected] for revision or set the order on revision via your portal.
Yes. We fund 100% of the project we cannot complete, late delivery and in rare case of failure to follow instructions.

Do You Need Homework Help?

We are experts in statistics, maths and homework tasks. Please check the articles below, they can help you understand your assignment