Calculate the standard error

Oct 13, 2025 by wbrum.org 145 views

**One Sample Has $$n=18$$ with $$SS=102$$ and \$$M=12$$. A Second Sample Has $$n=5$$ with $$SS=171$$ and \$$M=8$$. Which of the Following is the $$95\%$$ Confidence Interval for the Difference in Means?**

In statistics, a confidence interval is a range of values that is likely to contain the value of an unknown population parameter. When comparing two samples, we often want to know if there is a significant difference between the means of the two samples. In this article, we will discuss how to calculate the 95% confidence interval for the difference in means between two samples.

A confidence interval is a range of values that is likely to contain the value of an unknown population parameter. It is calculated using a sample of data and is used to estimate the population parameter. The confidence interval is usually expressed as a range of values, such as 10 to 20, which means that we are 95% confident that the true population parameter lies between 10 and 20.

To calculate the confidence interval for the difference in means between two samples, we need to follow these steps:

Calculate the standard error: The standard error is a measure of the variability of the sample means. It is calculated as the square root of the sum of the squared differences between the sample means and the population mean.
Calculate the margin of error: The margin of error is the maximum amount by which the sample mean may differ from the population mean. It is calculated as the product of the standard error and the critical value from the standard normal distribution.
Calculate the confidence interval: The confidence interval is calculated by adding and subtracting the margin of error from the sample mean.

The standard error is calculated as the square root of the sum of the squared differences between the sample means and the population mean. In this case, we have two samples with different sample sizes and means. We can calculate the standard error using the following formula:

SE = \sqrt{\frac{s_1^2}{n_1} + \frac{s_2^2}{n_2}}

where $s_1$ and $s_2$ are the sample standard deviations, and $n_1$ and $n_2$ are the sample sizes.

The margin of error is calculated as the product of the standard error and the critical value from the standard normal distribution. The critical value is a value that is used to determine the margin of error. For a 95% confidence interval, the critical value is 1.96.

ME = 1.96 \times SE

The confidence interval is calculated by adding and subtracting the margin of error from the sample mean.

CI = \bar{x}_1 - \bar{x}_2 \pm ME

where $\bar{x}_1$ and $\bar{x}_2$ are the sample means.

Let's use the data from the two samples to calculate the 95% confidence interval for the difference in means.

Sample 1: $$n=18$$ with $$SS=102$$ and $ $M=12$ $

Sample 2: $$n=5$$ with $$SS=171$$ and $ $M=8$ $

First, we need to calculate the standard error.

SE = \sqrt{\frac{102}{18} + \frac{171}{5}} = \sqrt{5.67 + 34.2} = \sqrt{39.87} = 6.31

Next, we need to calculate the margin of error.

ME = 1.96 \times 6.31 = 12.38

Finally, we can calculate the confidence interval.

CI = 12 - 8 \pm 12.38

CI = 4 \pm 12.38

Therefore, the 95% confidence interval for the difference in means is (-8.38, 16.38).

Q: What is the purpose of a confidence interval? A: The purpose of a confidence interval is to provide a range of values that is likely to contain the value of an unknown population parameter.

Q: How is the standard error calculated? A: The standard error is calculated as the square root of the sum of the squared differences between the sample means and the population mean.

Q: What is the margin of error? A: The margin of error is the maximum amount by which the sample mean may differ from the population mean.

Q: How is the confidence interval calculated? A: The confidence interval is calculated by adding and subtracting the margin of error from the sample mean.

Q: What is the critical value for a 95% confidence interval? A: The critical value for a 95% confidence interval is 1.96.

Q: How do I calculate the confidence interval for the difference in means between two samples? A: To calculate the confidence interval for the difference in means between two samples, you need to follow these steps:

Calculate the standard error.
Calculate the margin of error.
Calculate the confidence interval.

In this article, we discussed how to calculate the 95% confidence interval for the difference in means between two samples. We also provided a step-by-step guide on how to calculate the standard error, margin of error, and confidence interval. We hope that this article has provided you with a better understanding of how to calculate the confidence interval for the difference in means between two samples.