Researchers studying the abundance of sunfish want to investigate factors that contribute to how many fish live in sections of Lake Travis. So they sample different sections of the lake and measure the fish density (number of fish/cubic meter), as well as water temperature (°C), water pH, and whether or not there was a predator present. They ran the following multiple linear regression model with Fish Density as the response variable, confirmed all assumptions, and got the following results:
Estimate SE t | p-value 1.88 3.05 < 0.001 5.73 0.60 0.17 3.53 < 0.001 Intercept Water Temp (mean-centered) Water pH (mean-centered) Predator (O=No, 1=Yes) Water Temp* Predator 1.21 0.58 2.09 0.04 0.02 -2.76 -0.81 1.16 0.32 -2.38 -2.53 0.01 Model df = 54 Adjusted R2 = 0.236
a. Interpret the estimate for Water Temp in context, citing the appropriate statistics. Be specific.
b. Predict the fish density when predators are present at the mean water pH and at a water temperature that is 2oC above the mean. Round to two decimal places and don't include units.