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# Directional and nondirectional hypotheses

Directional and nondirectional hypotheses can be easily interchanged according to the hypothesis the researcher is testing. For instance, a drug

company might predict that a drug will help a subject lose weight while another drug company might predict that a drug will alter a subject’s

weight. Describe a situation in which you would test a directional hypothesis. Be sure to state the independent variables (e.g., drug or placebo) and the dependent variables (e.g., weight loss) clearly and explain why the hypothesis is directional. Then, revise the same situation to make it

nondirectional. Explain which according to you is more appropriate and why. Evaluate the practice of altering the alpha level so that a two-tailed

test will have a 5% rejection region on both sides of the curve for a total of 10% instead of having a 2.5% rejection region on both sides in order to maintain a 5% alpha. Justify your answers with appropriate reasoning and research from your textbook and course readings. Start reviewing

and responding to at least two of your classmates as early in the week as possible. You can ask technical questions or respond generally to the overall experience. Be honest, clear, and concise. Always use constructive language, even in criticism, to work toward the goal of positive

progress. Using questions and seeking clarifications are good ways to make your reviews substantive!

SOLUTIONS

Directional hypotheses are research hypotheses that predict the direction of the relationship between two variables. In other words, they suggest that one variable has an effect on the other variable in a specific direction. For example, a directional hypothesis might state that "increasing the amount of exercise will lead to a decrease in body weight."

On the other hand, non-directional hypotheses, also known as null hypotheses, do not predict the direction of the relationship between two variables. Instead, they suggest that there is no significant relationship between the two variables. For example, a non-directional hypothesis might state that "there is no significant difference in body weight between people who exercise and people who do not exercise."

Both types of hypotheses are important in research as they help guide the research questions and the data collection process. Directional hypotheses are useful when researchers have specific expectations about the relationship between two variables. Non-directional hypotheses are useful when researchers are not sure about the direction of the relationship and want to test if there is a significant relationship at all.

It is worth noting that null hypotheses are often used in statistical hypothesis testing to determine if there is a significant difference between two groups or if a treatment had a significant effect on an outcome. If the null hypothesis is rejected, then the directional hypothesis may be supported.