Because without representative sample, your results will not be valid.
It helps you nawser
If the sample is not representative of the population, then the characteristics of the sample are not the characteristics of the population. Example: If I want to estimate the percentage of the population that are men, and my sample is the school's football team, my estimate would be that 100% of the population is comprised of men. What went wrong with my survey ? Simple. The football team is not a representative sample of the population, at least not as regards gender.
A sample that accurately reflects the characteristics of the population as a whole
Take a simple random sample.
Many statistical statements for a population which are based on a sample are not valid if the sample is not representative.
Because without representative sample, your results will not be valid.
To generalize results from the sample population to the target population.
It helps you nawser
If the sample is not representative of the population, then the characteristics of the sample are not the characteristics of the population. Example: If I want to estimate the percentage of the population that are men, and my sample is the school's football team, my estimate would be that 100% of the population is comprised of men. What went wrong with my survey ? Simple. The football team is not a representative sample of the population, at least not as regards gender.
A representative sample is a randomly selected subset of the population.
A simple random sample.
A sample is any subset of the total population. A representative sample is one that is chosen so that its characteristics are similar to that of the population.
It is called a representative sample.
A sample that accurately reflects the characteristics of the population as a whole
That the key characteristics of the population are reflected in the sample.
Take a simple random sample.