Limitations and bias in a statistical analysis, what does it mean?

I have conducted a statistical analysis on Life Expectancy at Birth (years) in Africa and Europe. Now, I have been asked to find possible LIMITATIONS and BIAS in my analysis. What does it mean? Which limitations and bias are likely to be found in an analysis like the one I have just carried out?


May you please clarify this to me?


Many thanks!|||All of that depends strictly on what method you used to get the information in your analysis (which you might want to specify in an "additional comment"):





LIMITATIONS: What does the data say? Moreover, what doesn't it say, and does it really say what you need it to? For example, let's say you concluded that people in Africa generally have a shorter life expectancy than those in Europe. It would be beyond the limitations of the analysis to say that people in Europe are smarter than people in Africa.





BIAS: something in the experiment's which may have caused the experiment to lean in a certain direction.





Some examples:





Selection bias: where there is an error in choosing the individuals or groups to take part in a scientific study


biased sample: sometimes classified as a result of selection bias, is when some members of the population are more likely to be included than others.





Omitted-variable bias: the bias that appears in estimates of parameters in a regression analysis when the assumed specification is incorrect, in that it omits an independent variable that should be in the model