A student's confusion over Student's t-test values

[anisotropic]

Hello,

I've been working on this assignment for the past while, having to do with independent t-tests and the like. I have two major questions that I can't wrap my head around:

- When looking at the critical values of Student's t distribution table, what do you use as a critical value if your df value is not listed specifically? Say you need to know the critical value for a df of 120, but it only has the critical values for a df of 100 and a df of 140...
- On one of the [computer generated] analyses, I keep getting negative values for the t-value (-5.xxxx). I have no clue what this means. How is a negative number significant? Is it an error I've made?

 

[EnumaElish]

- Interpolate between 100 and 140.
- the numerator for the t value is = (statistic - hypothesis). If statistic < hypothesis then t < 0.

 

[tacman]

Thank you for reaching out with your questions. It's completely understandable to feel confused about Student's t-test values, as it can be a complex topic to grasp. Let me try to explain and clarify your concerns.

Firstly, when looking at a Student's t distribution table, the critical values listed are for specific degrees of freedom (df) values. Degrees of freedom refer to the number of values in a sample that are free to vary. In your example, if you need the critical value for a df of 120, you can use the critical value listed for a df of 100 and a df of 140 and interpolate between them. You can also use a statistical software or calculator to calculate the exact critical value for a specific df value.

Secondly, a negative t-value means that the sample mean is lower than the population mean. This can happen if the sample is significantly different from the population, or if there is an error in the data. It is important to check your data and calculations to ensure accuracy and to interpret the results correctly.

I hope this helps to clear up your confusion. If you have any further questions, please don't hesitate to ask. It's always better to seek clarification and fully understand the concepts rather than just memorizing formulas and numbers. Keep up the good work with your assignment!