T-statistic

Definition

The t-statistic is a statistical measure used to determine the probability that the difference between two sample means is due to chance. It is commonly employed in hypothesis testing to assess the significance of the difference between a sample mean and a hypothesized population mean, or the difference between two sample means.

5 Must Know Facts For Your Next Test

1. The t-statistic follows the Student's t-distribution, which is a bell-shaped curve that becomes more normal-like as the degrees of freedom increase.
2. The t-statistic is calculated by dividing the difference between the sample mean and the hypothesized population mean by the standard error of the sample mean.
3. In the context of a single population mean using the Student's t-distribution (topic 8.2), the t-statistic is used to determine if the sample mean is significantly different from the hypothesized population mean.
4. In the context of two population means with unknown standard deviations (topic 10.1), the t-statistic is used to determine if the difference between the two sample means is statistically significant.
5. The p-value associated with the t-statistic represents the probability of obtaining a test statistic at least as extreme as the one observed, given that the null hypothesis is true.

Review Questions

• Explain how the t-statistic is calculated and its role in hypothesis testing for a single population mean using the Student's t-distribution.
  • The t-statistic is calculated by dividing the difference between the sample mean and the hypothesized population mean by the standard error of the sample mean. In the context of a single population mean using the Student's t-distribution (topic 8.2), the t-statistic is used to determine if the sample mean is significantly different from the hypothesized population mean. The t-statistic follows the Student's t-distribution, which is used when the sample size is small and the population standard deviation is unknown. The t-statistic is then compared to a critical value from the t-distribution to determine the statistical significance of the difference between the sample mean and the hypothesized population mean.
• Describe the role of the t-statistic in hypothesis testing for the comparison of two population means with unknown standard deviations (topic 10.1).
  • In the context of comparing two population means with unknown standard deviations (topic 10.1), the t-statistic is used to determine if the difference between the two sample means is statistically significant. The t-statistic is calculated by dividing the difference between the two sample means by the standard error of the difference between the means. The t-statistic follows the Student's t-distribution, and the degrees of freedom are typically calculated as the sum of the sample sizes minus 2. The calculated t-statistic is then compared to a critical value from the t-distribution to determine the p-value and the statistical significance of the difference between the two sample means.
• Analyze the relationship between the t-statistic, the degrees of freedom, and the p-value in the context of hypothesis testing for both a single population mean and the comparison of two population means.
  • The t-statistic, degrees of freedom, and p-value are closely related in the context of hypothesis testing. The t-statistic is calculated based on the sample data and follows the Student's t-distribution, which is dependent on the degrees of freedom. The degrees of freedom are typically calculated as the sample size minus 1 for a single population mean, or the sum of the sample sizes minus 2 for the comparison of two population means. The p-value associated with the t-statistic represents the probability of obtaining a test statistic at least as extreme as the one observed, given that the null hypothesis is true. A lower p-value indicates a higher level of statistical significance, and the p-value is used to determine whether to reject or fail to reject the null hypothesis. The relationship between the t-statistic, degrees of freedom, and p-value is crucial in understanding the statistical significance of the results in both the single population mean and two population means scenarios.

Related terms

Student's t-distribution: The Student's t-distribution is a probability distribution used when the sample size is small, and the population standard deviation is unknown. It is used to calculate the t-statistic and determine the statistical significance of the difference between sample means.

Degrees of Freedom: Degrees of freedom refer to the number of values in a statistical analysis that are free to vary. In the context of the t-statistic, the degrees of freedom are typically calculated as the sample size minus 1.

Hypothesis Testing: Hypothesis testing is a statistical method used to determine whether a particular claim or hypothesis about a population parameter is supported by the sample data. The t-statistic is a key component in hypothesis testing, as it is used to calculate the p-value and determine the statistical significance of the results.