How do I determine a p-value??
I know that the pearson r = .48 and df = 18. Can I calculate it given only this information?
To calculate a p-value from the Pearson correlation coefficient (r), you need to know the sample size (n). The degrees of freedom (df) alone are not sufficient to calculate the p-value in this case.
The steps to calculate a p-value from r and n are as follows:
1. Determine the critical value for your desired significance level (e.g., α = 0.05). This critical value will depend on whether you are performing a one-tailed or two-tailed test, as well as the degrees of freedom.
2. Calculate the test statistic, t, by using the formula t = (r * sqrt(n - 2)) / sqrt(1 - r^2). Here, n is the sample size.
3. Determine the direction of the alternative hypothesis. If the alternative hypothesis is two-sided, divide the significance level (α) by 2.
4. Use the t-distribution table or a statistical software to find the area under the curve corresponding to your calculated t-value and degrees of freedom.
5. Compare this area (p-value) to your significance level. If the p-value is less than or equal to your significance level, you can reject the null hypothesis (H0).
In your case, you mentioned that r = 0.48 and df = 18, but the sample size (n) is missing. Without the sample size, it is not possible to calculate the p-value. Please ensure you have the necessary information (including n) to proceed with the calculation.