Question

"A government lobby that supports government regulation of the snack industry is looking into snack foods. Looking at a sample of 20 unhealthy snacks (e.g., sweets) they recorded the typical portion size in ounces and the calories per ounce of each snack. This data has been included below. Use Excel to calculate the correlation coefficient r between the two data sets. Round your answer to two decimal places."

Answer 1

This question is incomplete. Here is the data set attached in an image file.

The answer is -0.36.

Step-by-step explanation:

You must write down the input for both variables in a Excel spreadsheet. In another cell, you type the function: '=CORREL(array1,array2)' and you select all numeric values for 'oz/portion' as 'array1' and all numeric values for 'cal/oz' as 'array2'. To round it to two decimals, you type the function as: '=ROUND(CORREL(array1,array2),2)' where the 2 tells Excel how many digits you want to round the number to.

In this case with this dataset, the r correlation coefficient is equal to -0.36. This means that there is a negative correlation between the ounces per portion and the calories per ounce - the more ounces a portion has, the less calories per ounce it has. The correlation is moderate, not so strong, which could suggest that the portion size is determined to some extent by the caloric amount that the snack has, but there most certainly are other factors that determine the portion size.

The correlation formula that Excel uses is attached as well in another image file.