The article “Influence of Penetration Rate on Penetrometer Resistance” (J. Oliveira, M. Almeida, et al., Journal of Geotechnical and Geoenvironmental Engineering, 2011:695–703) presents measures of penetration resistance, expressed as a multiple of a standard quantity, for a certain fine-grained soil. Fifteen measurements taken at a depth of 1 m had a mean of 2.31 with a standard deviation of 0.89. Fifteen measurements taken at a depth of 2 m had a mean of 2.80 with a standard deviation of 1.10. Can you conclude that the penetration resistance differs between the two depths?