Q34.7-3ITD. - Campbell Biology

Question

Based on the value of r that you calculated in question 2, describe in words the correlation between mean brain volume of hominin species and the mean age of the species.

Step-by-Step Solution

Answer

The value of r suggests that the mean brain volume of hominin species and the mean age of the species are positively correlated because the correlation coefficient is greater than zero.

Step 1: Outline of the study

The mean brain volume of hominin species has changed over time because the brain volume of the earliest hominins ranged from 300 to 450 cm³. In contrast, the brain volume of modern humans ranges from 1200 to 1800cm³.

Thus, the researchers studied the mean brain volume and mean age of hominin species to determine the correlation between these two variables.

Step 2: Correlation coefficient ( r )

The correlation coefficient represents the amount and direction of a linear relationship between two variables. It is calculated using the following formula:

$r=\frac{\frac{1}{n-1}\sum (x_i-\overline{x)}(y_i-\overline{y})}{s_x{s}_y}$
 

Where x and y are the two variables, and n is the number of observations.

 

The value of r ranges from -1 to 1. A positive relationship between the two variables is shown by an r value greater than 1, while a negative relationship is indicated by an r value less than 1. 

 

Step 3: Correlation between mean brain volume and mean age of hominin species

The r estimated with the study's data is 0.407. Because r is greater than zero, it shows a positive relationship between the mean brain volume and the mean age of hominin species.