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Descriptive Statistics in Experimental Research
In experimental research studies where an independent variable is manipulated to create multiple groups and a quantitative dependent variable is measured, researchers typically compute descriptive statistics like means and standard deviations. The means from each experimental condition are calculated separately and then compared to determine if they differ from one another.
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Research Methods in Psychology - 4th American Edition @ KPU
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Correlation Coefficient
Sample Statistic
Descriptive Statistics in Experimental Research
Descriptive Statistics in Non-Experimental Research
Inferential Statistics
Understanding Descriptive Statistics
Scatterplot
Measures of Central Tendency
Measures of Dispersion
Forms of Statistical Relationship
Mean
Standard Deviation
Bar Graph
Line Graph
What is the primary purpose of using descriptive statistics in psychological research?
Match each category of descriptive statistics with the specific goal it accomplishes when a researcher is summarizing their data.
A researcher finds that a distribution of scores on a memory task is negatively skewed, meaning there are a few extremely low scores that pull the tail of the distribution to the left. Arrange the following measures of central tendency in order from the lowest numerical value to the highest numerical value based on this distribution's shape.
In a psychological study where a distribution of scores is highly skewed by a single extreme outlier, the mean is a more valid descriptive statistic than the median for evaluating the typical performance of the sample.
Measures of dispersion, such as the standard deviation and variance, are descriptive statistics used to describe the average scores within a research sample.
Tables in Research Reports
A psychologist studies the sleep patterns of college students and wants to summarize the collected data. Why must the psychologist report both a measure of central tendency (such as the mean) and a measure of dispersion (such as the standard deviation) to provide a complete descriptive summary of the sample's sleep duration?
A researcher records the number of errors made by five participants on a memory task: 3, 8, 2, 5, and 7. The range for this sample is _____.
A research team is summarizing data from a psychology study. Match each descriptive statistic on the left to the research situation on the right where it would be the most appropriate single summary to report.
A researcher reports that two groups of participants completed an identical mood-rating scale (scored 0–100). Group A had a mean of 60 and a standard deviation of 4, while Group B had a mean of 60 and a standard deviation of 22. Although both groups share the same measure of central tendency, a student analyzing these results should conclude that Group B's scores show substantially greater _____ than Group A's scores.
A researcher has collected scores on a stress questionnaire from 80 undergraduate participants and must decide which descriptive statistics to select and report. Arrange the following evaluative steps in the order that best supports an accurate, justified statistical summary of the data.
Define descriptive statistics and identify the two primary categories of quantitative techniques described in the text, including the specific measures associated with each.
Based on the case context, decide how the researcher should apply descriptive statistics to describe their data. Explain the two different types of measures the researcher needs to calculate and specify what each type of measure will communicate about the sample's performance.
A psychological researcher reports that a sample of participants completed a stress assessment, resulting in a mean score of and a standard deviation of . Explain what these specific descriptive statistics indicate about the scores of the participants in this sample.
Cohen's
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In experimental research where an independent variable is manipulated to create multiple groups and a quantitative dependent variable is measured, which descriptive statistics are typically computed and compared?
Arrange the following steps in the correct order to show how descriptive statistics are used to analyze results in experimental research.
A researcher conducts an experiment to see if the amount of sleep (4 hours vs. 8 hours) affects memory. Participants are assigned to one of two groups and then asked to recall words from a list. Match each research goal with the correct descriptive statistical procedure.
In an experiment where an independent variable is manipulated, calculating only the overall mean of the dependent variable for all participants combined would prevent a researcher from analyzing whether the manipulation produced different outcomes across the experimental conditions.
In experimental research, researchers typically calculate descriptive statistics like the mean for each experimental condition separately and then compare them to see if the groups differ.
In a study comparing the effectiveness of different therapeutic techniques on reducing anxiety, why would a researcher calculate the mean anxiety score for each therapy group separately?
A researcher claims that a new study technique is effective because the overall average test score for all participants is high. To evaluate this claim in an experimental design with two different conditions, the researcher must calculate the descriptive statistics for each condition _____ before comparing them.
A researcher investigates whether background music type (no music, classical, or pop) affects reading comprehension scores (0–20 points) in a three-group experiment. Match each element of the study to its correct description.
A researcher runs a two-group experiment examining the effect of mindfulness training (trained vs. untrained) on anxiety scores. After collecting data, she reports only a single combined mean anxiety score across all 60 participants. A classmate critiques this analysis, correctly pointing out that it makes it impossible to determine whether the _____ for the two groups actually differ — which is the core analytic goal when using descriptive statistics in experimental research.
A peer asks you to critically evaluate whether a published experiment correctly applied descriptive statistics to its multi-group data. Arrange the following evaluative steps in the order you should carry them out.
Based on the typical data analysis workflow for experimental research, identify the specific descriptive statistics that researchers calculate when they manipulate an independent variable to create multiple groups and measure a quantitative dependent variable. Explain how these values are used to evaluate the results of the experiment.
Explain why the researcher's approach is incorrect for analyzing this experiment. Detail what steps they should have taken instead using descriptive statistics, and how they should use those statistics to draw a conclusion about the conditions.
A psychologist conducts an experiment to test the effect of background noise level (quiet, moderate noise, loud noise) on test performance scores (measured quantitatively from to ). Apply the rules of experimental descriptive statistics to describe how the psychologist must calculate and compare the means to evaluate their data.