Psychology Statistics, statistics homework help

Respond to posting. Respond in one or more of the following ways:

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Margin of Error

The margin of errors works on clearing up the most expected differences between the actual population chosen and the selected sample. Additionally, we can use statistical theory to generate a confidence interval, which is known as the margin of errors. Usually specialist uses it with an aim to express the level of doubt relates to the sample data (Stangor, 2013). With regards to the sample size, according to our textbook, Stangor (2013) stated that the larger sample could deliver closer or more accurate estimates of the population. For example, a sample of 1000 people from small US town of 2000 people that is carefully selected, can report an exact estimate of the attitude in the US, purposing to cover 250 million people in the US in relating to the attitude.

I will explain more about the margin of errors through the selected article below

Child custody assessment: Afield survey of Spanish forensic psychologists practices

The research article in brief

Arch, Jarne, Peró, and Guàrdia, (2011) evaluated the divorce cases in Spain from 16,363 dissolutions of marriage in 1981 to 127,473 in 2010. Between children needs and parents’ responsibilities; forensic psychologists became critical about family and kids cases. Forensic psychologists conducted the methodically recommended evaluations (between parents, flexible custody), and these evaluation models should be valid, reliable instruments and criteria, linked to decision-making criteria. Furthermore, it is to adjust to Spain’s exact legal realities, which led them to combine the families. Due to not having a study by forensic psychology covers the sole custody in the Spanish legal context; this research study was created. The study ended with following a hierarchical decision-making model when deciding on sole custody approval by Spanish forensic psychologists (Arch et al., 2011).

Methods and results in brief

In the process, sixty-six Spanish forensic psychologist experts participated in the children custody evaluation to know the practice, procedure, and decision-making standards in family cases. Additionally, the size of the population was unidentified, and the estimate was below maximum indetermination (a 95% confidence level, a ± .06 margin of error set) (Arch et al., 2011).

In the material and instruments, Arch et al. (2011) used questionnaire based on the item, which was used by Keilin and Bloom (1986) and Ackerman and Ackerman (1997). Arch et al. collected the data using documents review, individual interviews (parent, kid), and observation. Additionally, with the aim to have the best result for both parents and child’s needs; the process was composed in three ways: a) forensic psychologist – Spain expert in child custody evaluation, b) partnership of twenty-three head offices of Spanish psychological association, and c) professionals in public Internet databases.

The result showed that in the decision-making stage; Spanish forensic psychologists follow a hierarchical model, starting with the high criteria’s concern to the child protection such as abuse, negligence, then moving on to parent’s capabilities (Arch et al., 2011)

Margin of error and the impacts on the results

The study reported that 66 participants enrolled in this study, to indicate the quality of the study results, the exports added the margin of error, which is ± .06, together with a confidence level of 95%. The percentage of confidence level indicates 95% of the confidence intervals containing the true population parameter, which is a high impact on this study results. For example, if the survey were repeated many times with diverse samples, then the true value (percentage) of the population would fall within the margin of error 95 percent of the time (Stangor, 2013).


Ackerman, M. J., & Ackerman, M. C. (1997). Custody evaluation practices: A survey of experienced professionals (revisited). Professional Psychology: Research and Practice, 28, 137-145. doi: 10.1037/0735-7028.28.2.137

Arch, M., Jarne, A., Peró, M., & Guàrdia, J. (2011). Child Custody Assessment: A field survey of Spanish Forensic Psychologists’ Practices. European Journal Of Psychology Applied To Legal Context, 3(2), 107-128.

Hart, S., Michie, C., & Cooke, D. (2007). Precision of actuarial risk assessment instruments: Evaluating the `margins of error’ of group v. individual predictions of violence. British Journal of Psychiatry, 190(suppl. 49), 60–65. Retrieved from

Imwinkelried, E. J. (1983). Standard for Admitting Scientific Evidence a Critique from the Perspective of Juror Psychology, The. Mil. L. Rev., 100, 99.

Keilin, W. G., & Bloom, L. J. (1986). Child custody evaluation practices: A survey of experienced professionals.Professional Psychology: Research and Practice, 17, 338-346. doi: 10.1037/0735-7028.17.4.338

Stangor, C. (2013). Research methods for the behavioral sciences (Laureate Education, Inc., custom ed.). Boston: Houghton Mifflin Company. (pp. 107-124 & 338–357)