Confidence interval inferential statistic Adds to the quality of the

# Confidence interval inferential statistic adds to the

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Confidence interval – inferential statistic Adds to the quality of the information o Allows researcher to draw conclusions about the population as a whole from the sample Range of values that is expected to include a population value a certain percentage of the time o We can be 95% sure that the interval calculated captures the population mean Non-overlapping confidence intervals o Indicate a substantial difference between the two different conditions of the study Power
Test has power if it results in a high probability that a difference that exists in reality will be found in the study o Inverse relationship with type II error Power = 1 – Beta [type two error] Affected by: alpha level, size of treatment effect [effect size], size of sample o With a small sample – low power and high chance of T2 error Best way to increase power of a study – increase sample size But, a huge sample can produce a result that is statistically significant but meaningless o Tiny, but statistically significant Chapter Twelve - Creating an effective survey o Adding demographic information [basic identifying information] Relevant demographic info may be determined by empirical question Only include important ones, put at the end of the survey o More include – longer survey, up likelihood of annoying respondent; may be seen as invasion if privacy o Survey wording – most important: pilot test on several people [to ensure they are all interpreting it the same way] Define any terms that could be interpreted different ways Three problems to avoid 1. Linguistic ambiguity 2. Asking two questions in one item 3. Leading questions
o Occurs often in business world – where the intent is to sell the product [be skeptical of business report] BK versus McDonals – flame broiled versus grilled Tips Simplicity better than complexity Use complete sentences Avoid most abbreviations Avoid slang and colloquial expressions Avoid jargon Avoid negatively phrased questions [not] Use balanced items [support or oppose better than do you support] - Surveys and ethics o Decisions that affect people’s lives are sometimes made through surveys People might be hurt or have times wasted if surveys are flawed/biased o Judicial system – set of standards for collecting survey data to use in a court of law [must collect is as a professional psychologist would] Thus pay attention to sampling, survey construction, data analysis

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