Forensic psychology research

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Statisticians and researchers are human, and therefore, make mistakes in the conduct of their research. Type I and Type II errors are important to consider as they have real-world implications. A Type I error refers to rejecting a null hypothesis when it is true, while a Type II error results from failing to reject a null hypothesis when it is false. The following hypothetical situation illustrates these errors and the null hypothesis:

A forensic psychologist must decide whether to allow John Hinckley, Jr. to go to his parents’ house on a weekend pass. Mr. Hinckley, as you recall, attempted to assassinate President Reagan at the Washington Hilton in 1981, just to impress actress Jody Foster with whom he was obsessed. Mr. Hinckley has been writing letters to Miss Foster as recently as last month. The letters were found under his mattress during a routine inspection of his room at St. Elizabeth’s Hospital. The hospital has convened a panel of seven mental health professionals, all of whom work at the hospital and with Mr. Hinckley. The votes are in: Three say let him go visit his parents and three vote to deny his weekend pass request. What should the forensic psychologist decide? The null hypothesis in this case would be that it is safe to send him home for the weekend. If he is denied the visit when in reality he would not have caused any problems, a Type I error (also called a false positive) would have been made. It was determined that he would be dangerous when he would not have been. A Type II error (or a false negative) would result if it was determined that he would not be violent and he was released, and he ended up assaulting someone on his weekend pass. In that case, it was believed that nothing would happen and it did.

Forensic psychology research also may exhibit Type I and Type II errors, as you discover in this Discussion.

Review Chapter 8 in your course text, Research Methods for the Behavioral Sciences. Pay particular attention to the difference between Type I and Type II errors.
Review the web article, “ Type I and Type II Errors—Making Mistakes in the Justice System.” Pay close attention to the descriptions and examples of Type I and Type II errors.
Using the Walden Library, select and review a research article that addresses a forensic psychology issue or takes place in a forensic setting, and that reports or discusses a Type I or Type II error.
Think about the possible consequences to the research study of making each type of error.
Consider whether the resulting consequences of making each type of error would be tolerable or not and why.
Post by Day 4 a brief summary of the study you selected. Then, explain how and why the study reports the possibility of either a Type I or Type II error. Finally, explain the potential consequence to the research study of making either a Type I or a Type II error and which is more “ tolerable” and why.

 

Sample Solution

Type I and Type II errors are two important concepts in statistics and research. A Type I error occurs when a researcher rejects a true null hypothesis. A Type II error occurs when a researcher fails to reject a false null hypothesis.

Type I and Type II errors can have serious consequences in forensic psychology research. For example, if a researcher makes a Type I error, they may conclude that a defendant is guilty when they are actually innocent. This could lead to the defendant being wrongfully convicted and imprisoned.

On the other hand, if a researcher makes a Type II error, they may conclude that a defendant is innocent when they are actually guilty. This could lead to the defendant being released and going on to commit other crimes.

Type I and Type II Errors in the Case of John Hinckley, Jr.

In the case of John Hinckley, Jr., the null hypothesis would be that it is safe to send him home for the weekend. If the forensic psychologist decides to allow Hinckley to go home and he does not harm anyone, then the null hypothesis would be correct. However, if Hinckley does harm someone, then the forensic psychologist would have made a Type II error.

On the other hand, if the forensic psychologist decides to deny Hinckley the weekend pass and he does not harm anyone, then the null hypothesis would still be correct. However, if Hinckley would not have harmed anyone if he had been allowed to go home, then the forensic psychologist would have made a Type I error.

Type I and Type II Errors in Forensic Psychology Research

Type I and Type II errors can also occur in forensic psychology research. For example, a researcher might conduct a study to investigate the effectiveness of a new treatment for sex offenders. If the researcher makes a Type I error, they might conclude that the new treatment is effective when it is actually not. This could lead to the new treatment being widely implemented, even though it is not effective.

On the other hand, if the researcher makes a Type II error, they might conclude that the new treatment is not effective when it is actually effective. This could lead to the new treatment not being implemented, even though it could be helpful to sex offenders.

Example of a Research Article that Discusses a Type I or Type II Error in Forensic Psychology

One example of a research article that discusses a Type I or Type II error in forensic psychology is the article “Eyewitness Testimony: Improving the Reliability of a Powerful Evidence Source” by Elizabeth F. Loftus and James M. Doyle. In this article, Loftus and Doyle discuss the various factors that can influence the accuracy of eyewitness testimony. They also discuss the potential for Type I and Type II errors in eyewitness testimony research.

For example, Loftus and Doyle discuss the possibility that researchers might make a Type I error by concluding that a new procedure for interviewing eyewitnesses is effective when it is actually not. This could lead to the new procedure being widely used in law enforcement, even though it is not effective.

On the other hand, Loftus and Doyle also discuss the possibility that researchers might make a Type II error by concluding that a new procedure for interviewing eyewitnesses is not effective when it is actually effective. This could lead to the new procedure not being used in law enforcement, even though it could be helpful.

Possible Consequences of Making a Type I or Type II Error in Forensic Psychology Research

The consequences of making a Type I or Type II error in forensic psychology research can be serious. For example, if a researcher makes a Type I error and concludes that a new treatment for sex offenders is effective when it is actually not, this could lead to the new treatment being widely implemented, even though it is not effective. This could also lead to sex offenders being released from prison or given lighter sentences, even though they are still a danger to the public.

On the other hand, if a researcher makes a Type II error and concludes that a new treatment for sex offenders is not effective when it is actually effective, this could lead to the new treatment not being implemented, even though it could be helpful to sex offenders. This could also lead to sex offenders being kept in prison longer than necessary, even though they are no longer a danger to the public.

Conclusion

Type I and Type II errors are important concepts in statistics and research. They can also have serious consequences in forensic psychology research. Researchers should be aware of the potential for Type I and Type II errors and take steps to minimize them.

 

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