3. Bivariate data often arises from the use of two different techniques to measure the same quantity. As an example, the accompanying observations on x 

hydrogen concentration (ppm) using a gas chromatography method and y  concentration using a new sensor method were read from a graph in the article A New Method to Measure the Diffusible Hydrogen Content in SteelWeldments Using a Polymer Electrolyte-Based Hydrogen Sensor (Welding Res., July 1997: 251s—256s).

x 47 62 65 70 70 78 95 100 114 118 y 38 62 53 67 84 79 93 106 117 116 x 124 127 140 140 140 150 152 164 198 221 y 127 114 134 139 142 170 149 154 200 215 Construct a scatter plot. Does there appear to be a very strong relationship between the two types of concentration measurements? Do the two methods appear to be measuring roughly the same quantity?

Explain your reasoning.