## Concept of Null Hypothesis in Research, its testing and understanding of: Levels of Confidence, tests of significance (one tailed and two tailed), Type-l & type-I errors.

One of the basic considerations you may need to consider for your descriptive statistics is whether to conduct a one-tailed or two-tailed hypothesis test. The sort of outcomes it can identify, the test’s statistical significance, and possible mistakes can all be significantly impacted by this decision.

## what is null hypothesis in research

A formal method for choosing between two explanations of a statistical connection in a sample is null hypothesis testing. The null hypothesis is one possible interpretation (typically represented by the sign H0 and written as “H-naught”). According to this theory, it has no connection with the population, and the association in the study is the result of sampling error. Unofficially, the sample association “occurred by chance,” according to the null hypothesis. The alternate hypothesis is the other interpretation (often symbolized as H1). This is the contention that a correlation existed overall and that the correlation in the sample accurately captures this connection.

## Definitions of Null Hypothesis in Research

• Significance level: ” In a hypothesis test, the significance level, alpha, is the probability of making the wrong decision when the null hypothesis is true.”
• Confidence level: “The probability that if a poll/test/survey were repeated over and over again, the results obtained would be the same. A confidence level =  1 – alpha.”
• Confidence interval: “A range of results from a poll, experiment, or survey that would be expected to contain the population parameter of interest.”

## Level of Confidence in Hypothesis Testing

Confidence intervals quantify how confident or problematic a sampling technique is. It can help to find out any number’s likelihood limitations, with a 95 percent or 99 percent confidence level being the most popular. The calculation of confidence intervals is done using statistical techniques like the t-test.

Statistical confidence intervals are used by statisticians to gauge the amount of skepticism in a sampling parameter. A diverse set of values that are constrained by the statistical mean and that are likely to include an unidentified sample population.

## The Test of Significance:

“A test of significance is a formal procedure for comparing observed data with a claim (also called a hypothesis), the truth of which is being assessed.”

• The declaration is a claim regarding a parameter, such as the population mean µ or percentage p.
• A likelihood is used to represent the positive screening findings and gauge how well the facts and the hypothesis coincide.

Some of the two most popular kinds of statistical reasoning is the use of confidence intervals. It is used by experts while attempting to quantify a population proportion. The purpose of the second frequent sort of inference, known as a test of significance, is to evaluate the data’s support for a statement about a population.

## Tails of a Test

In hypothesis testing, the whole set of respondents is transformed into a single number, called a statistical test. Some test numbers are presumably already recognizable to you. In hypothesis testing, the tails at either extreme of a distribution curve are referred to as tails. Obtaining all of the data samples and converting it to a single number is often what is meant by a test statistic in hypothesis testing.

## One Tail Test

Since one can only assess impacts in one direction, one-tailed hypothesis tests are often referred to as directional or one-sided tests. So this whole significance level percentage falls on the extreme side of one end of the distribution when a one-tailed test is used.

The important component of an allocation in a one-tailed test is one-sided, meaning that it can only be higher than or less than a specific number, never both. The alternative hypothesis should be accepted rather than the null hypothesis if the collection under investigation comes into the one-sided specified range. The one-tailed test is used by financial experts to verify an investment or stock assumption.

## Two Tail Test

A two-tailed test is created to ascertain, given a population parameter, whether a statement is correct or not. It looks at both ends of a particular data range, as indicated by the underlying posterior distribution. As a result, according to preset criteria, the probability distribution should depict the possibility of a certain occurrence.

## Difference between one-tailed and two-tailed test

A two-tailed hypothesis test is used to determine if the sampling distribution is substantially more or considerably less than the data obtained. But on the other hand,  a one-tailed hypothesis test is designed to demonstrate that the sampling distribution would either be greater or less than the data obtained.