Suppose a researcher investigates the relationship between iron deficiency and stunting in women throughout a developing nation. The researcher gathers a SRS of 68 women, and calculates an average height of 51.6 inches. In this population, stunting is considered any height below 56 inches with a population standard deviation of 0.4 inches. The researchers conclude that they must fail to reject the null hypothesis that women in this developing nation with iron deficiency are experiencing stunted growth. What type of error was potentially made here?