Excluding Outliers

Handling Valid Extreme Outliers

Example of an Outlier

Sensitivity of the Mean to Outliers

Defining Outliers using z Scores

Reaction Time Outlier Example

Impact of Outliers on the Range

Identifying Outliers Using z Scores

Handling Outliers

What term is used to describe an extreme score that falls significantly above or below the rest of the scores within a distribution?

In psychological research, an outlier in a dataset always indicates that an error occurred during data collection, such as an equipment malfunction or participant misunderstanding.

In psychological research, outliers can arise from various sources. Match each research scenario with the most likely reason for the extreme score described.

A researcher identifies a score in a dataset that falls significantly below the rest of the distribution. Arrange the following steps in the logical analytical sequence used to investigate and address this extreme value.

You are constructing a research protocol for a study on the cognitive effects of extreme stress. To ensure that your final dataset can systematically distinguish between genuine cases of 'stress resilience' (valid outliers) and 'task confusion' (measurement errors), which design element should you integrate into your data-collection phase?

Sexual Partners Survey Outlier Example

Outlier in Beck Depression Inventory Scores

A researcher is evaluating a dataset where a single participant's score is $150$, while all other scores are between $40$ and $60$. After confirming the participant understood the task perfectly and no errors occurred, the researcher decides to retain the score. This decision reflects a judgment that the extreme value is a(n) _____ which, despite its potential to skew the mean, represents a genuine and valid case within the study.

A researcher measures anxiety in 50 participants and finds that 49 scores fall between 20 and 45, but one participant scores 95. This extreme value, which may reflect a genuinely anxious individual or a data collection error, is called a(n) _____.

A researcher administering a depression inventory notices one participant scored far higher than the rest of the sample. If the researcher confirms this participant is indeed clinically depressed and no data entry or equipment errors occurred, this extreme score is no longer considered an outlier.

Match each description of a research scenario that produces an extreme score with its corresponding source of outlier.

When conducting data cleaning on a newly collected psychological dataset, order the stages a researcher should follow to systematically identify and categorize an extreme score.

Define what an outlier is in the context of a dataset's distribution, and describe the two broad categories of sources that can produce these extreme scores in psychological research.

Based on the provided context, diagnose the nature of this student's extreme score. Is this outlier a result of an error, or does it represent a genuine case? Explain your reasoning.

A researcher asks participants to report their age in years. Most responses range from $18$ to $22$. One participant enters $1999$. Apply the definition of an outlier to explain what this value represents and identify the most likely reason for this extreme score based on common sources of outliers.