Are people with bigger brains more intelligent? Forty college students volunteered to participate in a study which examined brain size (measured as 1000's of pixels counted in a brain scan), and IQ scores (measured in points). A scatterplot of the data is shown below.
-Select the best explanation for how one sample would be simulated in order to generate the null distribution.
A) Flip a coin to decide whether to swap the values for brain size and IQ or not. Plot the correlation coefficient of the randomized points on the null distribution.
B) Holding the order of brain size values constant, randomize the order of the IQs. Plot the correlation coefficient of the shuffled data on the null distribution.
C) Put each pair of (brain size, I
Q) on a piece of paper. Draw with replacement 40 times. Plot the correlation coefficient of the resampled data on the null distribution.
D) Add or subtract the appropriate value from each brain size and IQ in order to force the null hypothesis to be true. Plot the correlation coefficient of the shifted data on the null distribution.

Question

Are people with bigger brains more intelligent? Forty college students volunteered to participate in a study which examined brain size (measured as 1000's of pixels counted in a brain scan), and IQ scores (measured in points). A scatterplot of the data is shown below. 
-Select the best explanation for how one sample would be simulated in order to generate the null distribution.
A) Flip a coin to decide whether to swap the values for brain size and IQ or not. Plot the correlation coefficient of the randomized points on the null distribution. 
B) Holding the order of brain size values constant, randomize the order of the IQs. Plot the correlation coefficient of the shuffled data on the null distribution. 
C) Put each pair of (brain size, I
Q) on a piece of paper. Draw with replacement 40 times. Plot the correlation coefficient of the resampled data on the null distribution. 
D) Add or subtract the appropriate value from each brain size and IQ in order to force the null hypothesis to be true. Plot the correlation coefficient of the shifted data on the null distribution.

Quizplus · Accepted Answer

Randomizing the order of IQs while keeping brain size constant simulates the null hypothesis of no relationship, allowing for the generation of a null distribution of correlation coefficients.

Are People with Bigger Brains More Intelligent? Forty College Students