Height & weight
(Research hypothesis) H1: Greater height is positively correlated with higher weights amongst eight-year-olds.
(Null hypothesis) H0: There is no correlation between height and weight status amongst eight-year-olds.
Estimate: Positive correlation +
There is likely to be a strong correlation between increased height and weight in a population of children, but not a perfectly consistent correlation, given that some children may be short, but overweight, and others may be tall and thin.
GPA & the amount of weight lifted on a bench press test
H1: GPA is inversely correlated with weight lifted on a bench press test amongst senior male high school football players — the higher the GPA, the less weight the student can lift.
H0: GPA is not inversely correlated with weight lifted on a bench press test amongst senior male high school football players.
Estimate: No correlation or zero
Analysis: There may be a correlation, given that football players in their senior year are obviously dedicated to football, as they have spent four years playing the sport. If they can bench-press heavy weights, they may emphasize athletics at the expense of academics, in terms of how they prioritize their time. However, it is equally possible that in some schools, high-achieving students also use athletics as a way of bolstering their college resume. Factors such as the school, the degree to which athletics makes demands upon student athletes within the particular environment, and the intelligence of the players may indicate there is no correlation.
Daily air temperature & the average weight of clothing worn
H1: There is a negative correlation between temperature and weight of clothing — in other words, greater the air temperature, the lighter the clothing.
H0: There is no correlation between temperature and weight of clothing.
Estimate: Negative correlation -1
Analysis: The research hypothesis is likely to be proven, with only small variations for such factors as rain and humidity.
Shuttleworth, Martyn. Null hypothesis. Experiment Resources.com. 2008.
September 15, 2009 at http://www.experiment-resources.com/null-hypothesis.html