How do I make a hypothesis(es) to predict the effect of a manipulation of an independent variable on a quantitative dependent variable when flying an airplane?

Explain in simple language why knowing only these correlations enables you to say that prediction of manatee deaths from number of boats registered by a regression line will be much more accurate than prediction of a golfer's second‑round score from his first‑round score. Select the correct explanation from the choices.   A) The closer r is to 0 (in either direction), the stronger the linear relationship is between two variables.   B) Actually, prediction of manatee deaths from number of boats registered by a regression line will be much less accurate than prediction of a golfer's second‑round score from his first‑round score.   C) The fraction of the variation in the observed values of x explained by the least‑squares regression of y on x is given by r. The higher this fraction, the more likely that the prediction is accurate.   D) The further r is from 0 (in either direction), the stronger the linear relationship is between two variables.

A researcher plans to study the causal effect of police on crime using data from a random sample of U.K. counties. He plans to regress the county’s crime rate on the (per capita) size of the county’s police force. Explain why this regression is likely to suffer from omitted variable bias. Which variable would you add to the regression to controlfor important omitted variable? Determine whether the regression will likely over or underestimate the effect of police on the crime rate?

What are the different ways to reduce the error in least square regression?

How could we provide evidence for the positive association between two variables through linear regression model and hypothesis testing? What are the steps?

True or false: A proper line regression can be used to predict values of the response variable from absurd values of the explanatory variable.

A researcher is studying the intensity of hurricanes that entered the Gulf of Mexico between 1975-2015 and the average water temperature of the Gulf of Mexico at the hurricane's peak strength. What is the independent and dependent variable in this study?