Statistics, sample size determination

In summary, sample size is a crucial factor in statistics as it can impact the accuracy and reliability of the results. A larger sample size is generally preferred as it leads to more precise estimates and conclusions, and reduces the margin of error. The appropriate sample size for a study depends on various factors and can be determined using statistical formulas or online calculators. While a small sample size can still yield reliable results if properly representative and analyzed, having a sample size that is too small can lead to biased and unreliable results and make it difficult to detect meaningful relationships. There is no specific maximum sample size for a study, but it is important to consider the law of diminishing returns when determining the sample size.
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Homework Statement


Glucose level is normally distributed, standard deviation is known to be 25 units; determine the sample size needed to be 95% confident that the sample mean and the true population mean differ by at most 4 units.


Homework Equations


(work shown below)


The Attempt at a Solution


Margin of error = 4 units
Margin of error = z * standard error
4=1.96 * (25/(n)^1/2)
4 = (49) / (n)^1/2
49 = 4(n)^1/2
(12.25)^2 = (n^1/2)^2
n=151
 
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.5625 Therefore, the sample size needed to be 95% confident that the sample mean and the true population mean differ by at most 4 units is 152.
 

1. What is the importance of sample size in statistics?

Sample size is an important factor in statistics because it affects the accuracy and reliability of the results. A larger sample size is generally more representative of the population and can lead to more precise estimates and conclusions. It also helps to reduce the margin of error in the data.

2. How do I determine the appropriate sample size for my study?

The appropriate sample size for a study depends on various factors such as the desired level of accuracy, confidence level, and variability of the data. There are statistical formulas and online calculators available to help determine the sample size needed for a specific study design and research question.

3. Can a small sample size still yield reliable results?

Yes, a small sample size can still yield reliable results if it is representative of the population and the data is properly analyzed. However, a larger sample size is generally preferred as it increases the chances of getting accurate and precise results.

4. What are the consequences of having a sample size that is too small?

Having a sample size that is too small can lead to biased and unreliable results. It can also make it difficult to detect meaningful relationships or differences in the data. Additionally, a small sample size may not provide enough statistical power to accurately answer the research question.

5. Is there a maximum sample size for a study?

There is no specific maximum sample size for a study. It depends on the research question, study design, and available resources. However, it is important to consider the law of diminishing returns, where increasing the sample size beyond a certain point may not significantly improve the results and may not be worth the additional time and resources.

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