Exam 7: Correlational Research
When one's data are on an ordinal scale of measurement, a _________ correlation should be used.
A
When a correlation is statistically significant, we know that it
C
Why is it important to examine the scatterplot of the relationship between two variables when doing correlational research?
Examining the scatterplot of the relationship between two variables when doing correlational research is important for several reasons:
1. Visual Representation of Data: A scatterplot provides a visual representation of the data points for each pair of variables. This allows researchers to see the overall pattern of the relationship at a glance, which can be more intuitive than looking at correlation coefficients alone.
2. Identifying the Nature of the Relationship: Scatterplots help in identifying the nature of the relationship between variables, whether it is positive (both variables increase together), negative (one variable increases as the other decreases), or non-linear (the relationship changes in direction across the range of values).
3. Detecting Outliers: Outliers are data points that do not fit the general pattern of the data. Scatterplots make it easier to spot these outliers, which can have a significant impact on the correlation coefficient and may indicate errors in data collection, entry, or unusual conditions that warrant further investigation.
4. Assessing Linearity: Correlation coefficients measure the strength and direction of a linear relationship between two variables. By examining a scatterplot, researchers can determine if the relationship is indeed linear or if it takes on a more complex form, such as curvilinear or cyclical, which cannot be adequately captured by a simple correlation coefficient.
5. Checking for Homoscedasticity: Homoscedasticity refers to the consistency of the spread of data points around the line of best fit. In a scatterplot, researchers can check for homoscedasticity to ensure that the variance of one variable is roughly the same across all values of the other variable. Heteroscedasticity, where the spread of data points varies, can affect the validity of correlation results.
6. Understanding the Strength of the Relationship: While the correlation coefficient quantifies the strength of the relationship, a scatterplot can provide a more nuanced understanding. For example, a very high or very low correlation coefficient might be influenced by a few data points. A scatterplot helps to contextualize the coefficient by showing the concentration and dispersion of data points.
7. Identifying Potential Causal Relationships: Although correlation does not imply causation, scatterplots can help in hypothesizing potential causal relationships that might be explored through further research, including experimental or longitudinal studies.
8. Preparing for Further Analysis: Scatterplots can be used as a preliminary step before conducting more sophisticated statistical analyses, such as regression. They help in assessing the assumptions required for these analyses and in determining the appropriate form of the regression equation.
In summary, examining scatterplots is a crucial step in correlational research because it provides a comprehensive view of the data, helps in identifying patterns and anomalies, and informs the interpretation of statistical measures of correlation.
A researcher predicts that variable X has a positive relationship with variable Y. This is a
The formula for the correlation coefficient, as we know it today, was devised by
A correlation of +.90 is _________ times as strong as a correlation of +.30.
Most correlational research satisfies which of the following criteria for determining whether one variable causes another?
Discuss three factors that can distort the value of a correlation coefficient.
A researcher obtained a correlation of +.52 between Variable A and Variable B. What is the best interpretation of this correlation?
The correlation between anxiety and depression is +.45. Interpret this correlation.
If the partial correlation between Variables X and Y is equal to the Pearson correlation between X and Y,
What is an outlier? What effect do outliers have on correlation coefficients?
Having found that people from similar socioeconomic backgrounds are more likely to become friends than people from different backgrounds, a researcher wanted to test the hypothesis that this effect is due to the fact that people from the same socioeconomic background are more likely to share similar attitudes. What could the researcher use to examine this hypothesis?
Why should a researcher not interpret a correlation that is not statistically significant?
A researcher is correlating gender (male/female)with whether adolescents have had sexual intercourse (no/yes). What kind of correlation should he use?
Distinguish between a positive and a negative correlation. Draw what a positive versus a negative correlation might look like on a scatterplot.
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