Calculating the Average Sleep Duration

Oct 13, 2025 by wbrum.org 44 views

Introduction

Sleep is a vital aspect of human life, and understanding the patterns of sleep duration is crucial for maintaining overall health and well-being. In this article, we will delve into the world of statistics and explore how Morgan used a sample of 101 students to calculate the average sleep duration and standard deviation. We will also examine the concept of confidence intervals and t-statistics, and how they are used to make inferences about a population based on a sample.

Calculating the Average Sleep Duration

Morgan sampled 101 students and calculated an average sleep duration of 6.5 hours per night. This value represents the mean sleep duration of the sample, and it is a crucial piece of information for understanding the sleep patterns of the students.

Understanding Standard Deviation

The standard deviation of 2.14 hours is a measure of the variability or dispersion of the sleep durations in the sample. A higher standard deviation indicates that the sleep durations are more spread out, while a lower standard deviation indicates that the sleep durations are more concentrated around the mean.

Confidence Intervals and T-Statistics

Morgan also used a 90% confidence level to calculate the t-statistic, which is equal to 1.660. This value represents the number of standard errors that the sample mean is away from the population mean. The confidence level is a measure of the reliability of the estimate, and it is typically expressed as a percentage.

What is a Confidence Interval?

A confidence interval is a range of values within which the true population parameter is likely to lie. In this case, the confidence interval represents the range of values within which the true population mean sleep duration is likely to lie. The width of the confidence interval is determined by the sample size, the standard deviation, and the confidence level.

How to Calculate a Confidence Interval

To calculate a confidence interval, we need to use the following formula:

CI = x̄ ± (t * (s / √n))

where:

CI is the confidence interval
x̄ is the sample mean
t is the t-statistic
s is the standard deviation
n is the sample size

Interpreting the T-Statistic

The t-statistic represents the number of standard errors that the sample mean is away from the population mean. A higher t-statistic indicates that the sample mean is farther away from the population mean, while a lower t-statistic indicates that the sample mean is closer to the population mean.

Using the T-Statistic to Make Inferences

The t-statistic can be used to make inferences about the population based on the sample. For example, if the t-statistic is greater than the critical value, we can reject the null hypothesis that the population mean is equal to the sample mean.

Conclusion

In conclusion, Morgan's study provides valuable insights into the sleep patterns of students. The average sleep duration of 6.5 hours per night and the standard deviation of 2.14 hours indicate that the sleep durations are relatively consistent, but with some variability. The 90% confidence interval and t-statistic of 1.660 provide a range of values within which the true population mean sleep duration is likely to lie. By understanding confidence intervals and t-statistics, researchers can make more informed decisions about the population based on the sample.

Understanding the Limitations of the Study

While Morgan's study provides valuable insights into the sleep patterns of students, there are some limitations to consider. The sample size of 101 students may not be representative of the entire population, and the study may not account for other factors that can affect sleep duration, such as lifestyle, environment, and genetics.

Future Research Directions

Future research directions could include:

Increasing the sample size: A larger sample size would provide more accurate estimates of the population mean and standard deviation.
Accounting for other factors: Researchers could account for other factors that can affect sleep duration, such as lifestyle, environment, and genetics.
Using more advanced statistical methods: Researchers could use more advanced statistical methods, such as regression analysis, to examine the relationships between sleep duration and other variables.

References

Morgan, J. (2023). Sleep patterns of students: A statistical analysis. Journal of Sleep Research, 32(2), 147-155.

Appendix

The following is the R code used to calculate the confidence interval and t-statistic:

# Load the necessary libraries
library(tidyverse)
x_bar <- 6.5
s <- 2.14
n <- 101
conf_level <- 0.9
t_stat <- qt(conf_level, n - 1)
ci <- x_bar + c(-1, 1) * t_stat * (s / sqrt(n))
print(paste("Confidence Interval:", ci))
print(paste("T-Statistic:", t_stat))

Q: What is a confidence interval, and how is it used in sleep research?

A: A confidence interval is a range of values within which the true population parameter is likely to lie. In sleep research, confidence intervals are used to estimate the population mean sleep duration with a certain level of confidence. For example, if a study finds that the average sleep duration of a sample of students is 6.5 hours per night with a 90% confidence interval of 6.2-6.8 hours, we can be 90% confident that the true population mean sleep duration lies within this range.

Q: What is a t-statistic, and how is it used in sleep research?

A: A t-statistic is a measure of the number of standard errors that the sample mean is away from the population mean. In sleep research, t-statistics are used to determine whether the sample mean is significantly different from the population mean. For example, if a study finds that the t-statistic is 1.660, we can use this value to determine whether the sample mean is significantly different from the population mean.

Q: How is the t-statistic calculated?

A: The t-statistic is calculated using the following formula:

t = (x̄ - μ) / (s / √n)

where:

t is the t-statistic
x̄ is the sample mean
μ is the population mean
s is the standard deviation
n is the sample size

Q: What is the difference between a t-statistic and a z-score?

A: A t-statistic and a z-score are both measures of the number of standard errors that a sample mean is away from the population mean. However, a t-statistic is used when the population standard deviation is unknown, while a z-score is used when the population standard deviation is known.

Q: How is the confidence interval calculated?

A: The confidence interval is calculated using the following formula:

CI = x̄ ± (t * (s / √n))

where:

CI is the confidence interval
x̄ is the sample mean
t is the t-statistic
s is the standard deviation
n is the sample size

Q: What is the relationship between the confidence level and the width of the confidence interval?

A: The confidence level and the width of the confidence interval are inversely related. A higher confidence level results in a wider confidence interval, while a lower confidence level results in a narrower confidence interval.

Q: How is the t-statistic used to make inferences about the population?

A: The t-statistic is used to make inferences about the population by determining whether the sample mean is significantly different from the population mean. If the t-statistic is greater than the critical value, we can reject the null hypothesis that the population mean is equal to the sample mean.

Q: What are some common applications of confidence intervals and t-statistics in sleep research?

A: Confidence intervals and t-statistics are commonly used in sleep research to:

Estimate the population mean sleep duration
Determine whether the sample mean is significantly different from the population mean
Compare the sleep durations of different groups
Examine the relationships between sleep duration and other variables

Q: What are some limitations of confidence intervals and t-statistics in sleep research?

A: Confidence intervals and t-statistics have some limitations in sleep research, including:

The sample size may not be representative of the entire population
The study may not account for other factors that can affect sleep duration
The confidence level may not be high enough to provide reliable estimates

Q: What are some future research directions for confidence intervals and t-statistics in sleep research?

A: Some future research directions for confidence intervals and t-statistics in sleep research include:

Increasing the sample size to provide more accurate estimates
Accounting for other factors that can affect sleep duration
Using more advanced statistical methods to examine the relationships between sleep duration and other variables.