What is the difference between a population and a sample in statistics?

Answer) In statistics, the population is the set of entities such as a mean height of men. The mean height of men includes all men existed, living, or will be lived in the world so it is a hypothetical population. It is typically impossible to measure or survey the whole population because every member is not observable. If men are population then their height is a parameter of interest. On the other hand, the subset taken of the population for measurement or survey purpose is known as a sample, and inferences about the population are drawn from the sample, given certain conditions.

How to interpret confidence intervals and confidence levels?

Answer) While creating the confidence interval, its interpretation is important to get the meaning confidence level used in the study along with the interval that is obtained. A range of plausible values is given by a specific confidence interval for the parameter of interest while confidence level refers to the success rate in long-term of the method. Usually, 95% confidence interval is computed for the sample. It can be interpreted as an interval having 0.95 probability of covering population mean. While taking sample results and constructing 90% confidence interval can be interpreted as about 90% of the sample will respond to the research.

Why the p-value is important?

Answer) The p-value has a significant importance and it can be perceived as the oracle that judges the results of the study. If the p-value is 0.05 or less than 0.05, it can be considered the results are significant, but if its value is greater than 0.05, the result is considered non-significant. The size of p-value may have a significant impact on issues like financial condition, clinical practices, and publication and career success of researchers. There are two hypotheses on which p-value is based, and it is normally assumed that there is no effect or difference of an exposure. The p-value plays an important role when the results of the study are being discussed that shows its importance.