Final answer:
If the obtained t-test value is equal to or higher than the critical value, you should reject the null hypothesis because this suggests that the data are not likely to have occurred if the null hypothesis were true. The correct answer is B) Reject the null hypothesis.
Step-by-step explanation:
If the obtained t-test value is equal to or higher than the critical value, you should reject the null hypothesis. This is because a higher t-test value compared to the critical value indicates that the observed data are sufficiently unlikely under the assumption that the null hypothesis is true. Hence, more evidence exists in favor of the alternative hypothesis.
To decide on the null hypothesis, one can use two methods:
Method 1: Compare the p-value to the significance level (α). If the p-value is less than or equal to α, reject the null hypothesis.Method 2: Compare the t-test value to the critical value from a t-distribution table. If the t-test value is greater than or equal to the critical value at the chosen α, reject the null hypothesis.
It is essential to decide whether to conduct a one-tailed or two-tailed test before analyzing the data. This decision is based on the research hypothesis being tested.