A researcher is interested in the relationship between caffeine intake and short-term memory. On each day over a period of a few weeks, the researcher randomly assigned a daily caffeine intake to each person and measured their performance on a short-term memory test. The resulting data had a correlation coefficient of −0.75. Can the researcher conclude that caffeine causes an decrease in short-term memory? Explain. (1 point)
Responses
No. The researcher did not control the caffeine intake, so the data only show correlation.
Yes. The researcher controlled the memory test scores, so the correlation in the results implies a cause-and-effect relationship.
Yes. The researcher controlled the caffeine intake, so the correlation implies causation.
No. The researcher did not control the memory test scores, so the data only show correlation.
No. The researcher did not control the caffeine intake, so the data only show correlation.
No. The researcher did not control the caffeine intake, so the data only show correlation.
The correct answer is: No. The researcher did not control the caffeine intake, so the data only show correlation.
To understand why this is the correct answer, let's break down the reasoning:
The researcher conducted an experiment where they randomly assigned a daily caffeine intake to each person over a period of a few weeks. They then measured their performance on a short-term memory test. The resulting data had a correlation coefficient of −0.75.
A correlation coefficient measures the strength and direction of the linear relationship between two variables, in this case, caffeine intake and short-term memory performance. The correlation coefficient of −0.75 indicates a strong negative correlation, suggesting that as caffeine intake increases, short-term memory performance tends to decrease.
However, correlation does not imply causation. This means that just because there is a correlation between caffeine intake and short-term memory performance, it does not necessarily mean that one variable causes the other.
In this case, it is important to note that the researcher did not control the caffeine intake. Instead, they randomly assigned a daily caffeine intake to each person. Without controlling the variable being studied (in this case, caffeine intake), it is not possible to establish a cause-and-effect relationship.
Therefore, the researcher cannot conclude that caffeine causes a decrease in short-term memory based solely on this correlation.