Learn Before
Identifying Outliers Using z Scores
scores provide a quantitative method for defining outliers within a distribution. Commonly, an outlier is defined as any score that is more than three standard deviations away from the mean, which corresponds to a score less than or greater than .
0
1
Tags
KPU
Research Methods in Psychology - 4th American Edition @ KPU
Related
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 , while all other scores are between and . 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.
Learn After
When using z scores to quantitatively define outliers within a distribution, a score is commonly considered an outlier if it is more than how many standard deviations away from the mean?
A researcher calculates z scores for all participants' reaction times in a cognitive psychology experiment. One participant receives a z score of −2.85. Using the conventional z-score criterion for identifying outliers (i.e., more than three standard deviations from the mean), this participant's reaction time would be classified as an outlier.
In a cognitive psychology experiment measuring reaction times, the sample mean is 400 ms with a standard deviation of 50 ms. Using the standard criterion for outliers (scores with a z score greater than +3.00 or less than -3.00), match each of the following participant reaction times to its correct classification and calculated z score.
In a study investigating adolescent sleep patterns (Mean = 7.5 hours, Standard Deviation = 0.5 hours), a researcher uses z scores to identify potential outliers. Arrange the following sleep durations in order from the least extreme (closest to the mean) to the most extreme (furthest from the mean) to determine which value meets the common criterion for being a statistical outlier.
You are designing a clinical diagnostic scale to identify children with 'extreme social anxiety.' To ensure your tool follows standard statistical conventions for identifying outliers, you want to establish the scoring parameters such that a raw score of on the scale corresponds exactly to the outlier threshold of . If the population mean () is fixed at , what standard deviation () must you ensure the test produces during its standardization phase to meet this design requirement?
According to the common statistical convention in psychological research, a score is classified as an outlier if it has a corresponding score that is less than or greater than .
In psychology research, when evaluating the effectiveness of the score method for outlier detection, researchers must recognize that extreme values can paradoxically mask their own extremity by significantly _____ the standard deviation.
A cognitive psychologist calculates scores for a dataset of reaction times with a mean of 500 ms and a standard deviation of 50 ms. Match each participant's raw score to its correct classification based on the standard score outlier threshold.
An analyst is identifying outliers in a dataset. They note that a score is quantitatively classified as an outlier if it is more than _____ standard deviations away from the mean, representing a score less than or greater than .
Evaluate the extremity of the following participant scores and order them from the most extreme low-value outlier to the most extreme high-value outlier based on the standard outlier threshold of .