Calculate a chi-square value for this example in the space below. What conclusion(s) could you draw from the data?

Question

Studies show that the following are the approximate frequencies of the various ABO blood types in the U.S.: 39% A, 12% B, 4% AB, and 45% O. Do the data given in the following table represent a satisfactory sample of the U.S. population? Complete Table 6, calculate the X2, and answer the questions based on your calculations. Calculate E values to the nearest one-hundredth (0.01).

Studies show that the following are the approximate frequencies of the various ABO blood types in the U.S.: 39% A, 12% B, 4% AB, and 45% O. Do the data given in the following table represent a satisfactory sample of the U.S. population? Complete Table 6, calculate the X2, and answer the questions based on your calculations. Calculate E values to the nearest one-hundredth (0.01).

1. Calculate a chi-square value for this example in the space below.
2. What conclusion(s) could you draw from the data?

Answer 1

1.Chi square is given by the following equation: X²=∑ (O-E)² ÷ E

where O is the observed frequency, and E is the expected frequency.

We could infer that E is 25% for each blood group (100÷4).

2.As for drawing a conclusion, after calculating your chi-square value, just based on the data given, it is pretty clear that x² ≠ 0, therefore the actual blood type frequencies aren't as neatly grouped in the real world. The next step would be to determine if this variation is from chance alone, or whether there might be an underlying factor that is influencing the blood type frequencies.

To determine this, you will need your x² values, the degrees of freedom (number of categories - 1; so 4 blood type groups - 1), and a chi-square distribution table (can be found with a simple google search). The p-value could be used to reach a conclusion.