The water department checks the city water supply on a regular basis for contaminants such as xylenes. the water department takes 200 samples and estimates that the concentration of xylenes in your drinking water is 3.5 ppb (parts per billion), with a standard deviation of 0.2 ppb.

assuming the samples were random and unbiased, how much confidence can you have in this data?

A simple random sample is meant to be an unbiased representation of a group. It is considered a fair way to select a sample from a larger population since every member of the population has an equal chance of getting selected.

What is an unbiased random sample?

A sample drawn and recorded by a method which is free from bias. This implies not only freedom from bias in the method of selection, e.g. random sampling, but freedom from any bias of procedure, e.g. wrong definition, non-response, design of questions, interviewer bias, etc.

What is the difference between random and biased?

Participants in random samples are simply chosen at random. On the other hand, biased samples always have problems. They portray an image that is out of line with the real truth, which means that they are useless to most people

What is unbiased data?

In statistics, the word bias — and its opposite, unbiased — means the same thing, but the definition is a little more precise: If your statistic is not an underestimate or overestimate of a population parameter, then that statistic is said to be unbiased

To learn more about unbiased and biased, refer

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