You have 40 genetically similar parsley plants (Cultivar X88), each in their own pot, and a greenhouse with little microhabitat variation. You use a coin to assign each plant to either a spring water treatment (heads) or a tap water treatment (tails) until you have 20 plants assigned to each treatment. After a month you collect data on how much each plant has grown.

ASSUME YOU COLLECTED THE FOLLOWING DATA

Spring water:

Mean height grown 5.2 cm Standard deviation 0.5 cm n=20

Tap Water

Mean height grown 7.3 cm Standard deviation 0.7 cm n=20

Test whether there is a significant difference in the amount Cultivar X88 parsley plants have grown on spring water versus tap water. Assume data meet the assumption of normality and use=0.05

a) State the question (ID the population)

b) State your null and alternative hypotheses (define symbols)

c) Analyze your data statistically

d) Using the following online calculator, determine the p-value for your t* value. http://epitools.ausvet.com.au/content.php?page=2-sample-t-test be sure to choose correct number of tails for the test (one vs. two tailed). NOTE: you should report t* from this online calculator.

e) Provide a statement of conclusion that includes the statistical evidence and makes inference back to the population.

NOTE on p-values: If you have an exact p-value you should give it. Typically you round to the hundredth place. The exception is if the p-value is very small. Since small p-values suggest stronger statistical evidence we like to report these to greater significant digits, typically we stop at 0.0001. If you every encounter a p-value that looks like 0.00000 - just add a 1 at the end and report at p<0.00001