The life of a theory is durable which can be changed or modified when a new hypothesis is generated on the same issue or scientific question which explains the phenomenon more accurately. The advancement in the technology can add knowledge to the existed theory which could lead to the modification of the theory.

A useful theory that has been tested and supported may become a dominant view among the majority of scientists. However, science is always changing. As new evidence is uncovered, a theory may be revised or replaced by a more useful explanation.

Scientists are likely to accept a new or modified theory if it explains everything the old theory did and more. The process of theory change may take time and involve controversy, but eventually the scientific explanation that is more accurate will be accepted.

Like theories, scientific laws describe phenomena that the scientific community has found to be provably true. Generally, laws describe what will happen in a given situation as demonstrable by a mathematical equation, whereas theories describe how the phenomenon happens.

Statistical analysts test a hypothesis by measuring and examining a random sample of the population being analyzed. All analysts use a random population sample to test two different hypotheses: the null hypothesis and the alternative hypothesis.

The p-value is a number, calculated from a statistical test, that describes how likely you are to have found a particular set of observations if the null hypothesis were true. P-values are used in hypothesis testing to help decide whether to reject the null hypothesis.

statistically significant

The level of significance which is selected in Step 1 (e.g., α =0.05) dictates the critical value. For example, in an upper tailed Z test, if α =0.05 then the critical value is Z=1.645.

Typical values for are 0.1, 0.05, and 0.01. These values correspond to the probability of observing such an extreme value by chance. In the test score example above, the P-value is 0.0082, so the probability of observing such a value by chance is less that 0.01, and the result is significant at the 0.01 level.

The smaller the p-value, the stronger the evidence that you should reject the null hypothesis. A p-value less than 0.05 (typically ≤ 0.05) is statistically significant. A p-value higher than 0.05 (> 0.05) is not statistically significant and indicates strong evidence for the null hypothesis.

Rejecting or failing to reject the null hypothesis If our statistical analysis shows that the significance level is below the cut-off value we have set (e.g., either 0.05 or 0.01), we reject the null hypothesis and accept the alternative hypothesis.

As an example if your level of significance is 0.05, the correspondent t-stat value is 1.96, thus when the t-stat reported in the output is higher than 1.96 you reject the null hypothesis and your coefficient is significant at 5% significance level.

This means that the results are considered to be „statistically non-significant‟ if the analysis shows that differences as large as (or larger than) the observed difference would be expected to occur by chance more than one out of twenty times (p > 0.05).

Compare the P-value to the α significance level stated earlier. If it is less than α, reject the null hypothesis. If the result is greater than α, fail to reject the null hypothesis. If you reject the null hypothesis, this implies that your alternative hypothesis is correct, and that the data is significant.

The one-way analysis of variance (ANOVA) is used to determine whether there are any statistically significant differences between the means of two or more independent (unrelated) groups (although you tend to only see it used when there are a minimum of three, rather than two groups).