Researchers measured the number of neurons in the CA1 region of the hippocampus in the brains of eight persons who had died of causes unrelated to brain function. They found that these data were negatively correlated with age. The sample value of r was -0.63.7
(a) Consider testing whether the population correlation is zero. State the null and alternative hypotheses in symbols.
(b) How many degrees of freedom are there for the test in part (a)?
(c) Compute the value of the test statistic.
(d) The P-value for the test is 0.094. If a = 0.10, what is your conclusion regarding the null hypothesis?