Final answer:
The appropriate number of samples to take from one site to ensure confidence in measurement results varies, but general guidelines suggest a few hundred observations, or more based on statistical rules of thumb and the nature of the population distribution. Larger samples tend to be more reliable, and the minimum sample size should consider possible variation in samples and the normalcy of the population distribution.
Step-by-step explanation:
In order to have confidence in the values obtained from your measurement, the number of samples you should take from one site depends on various factors, including the variability of the data, the desired precision of the results, and the population size. Generally, for many applications, samples of a few hundred observations may suffice. However, for polling purposes, larger samples ranging from 1,200 to 1,500 observations are seen as adequate if the survey is random and well-conducted. It's also recommended that the population size be at least 10 to 20 times the size of the sample to prevent oversampling and ensure accurate results. Moreover, a minimum sample size of 30 is suggested if the original population has a normal distribution or at least more observations are needed if the distribution is far from normal.
When determining the sample size, there's a recognition that larger samples are more reliable. The rules of thumb emerging from statistical literature and experiences can guide what is considered sufficient. If the statistical findings from multiple samplings are significantly different, it may indicate a need to review the methods or to consider that there's inherent variation in samples, which decreases as sample size increases.
It's essential to remember that there's always uncertainty in measurements, especially those derived from graphs. If your measurements do not align with expectations, they should be within the estimated uncertainties. In summary, while there are general guidelines, the appropriate sample size will ultimately be influenced by the specifics of each situation.