River Project What are the types of sampling and how is each accomplished?

Harvest Time A farmer has just cleared a new field for corn. It is a unique plot of land in that a river runs along one side. The corn looks good in some areas of the field but not others. The farmer is not sure that harvesting the field is worth the expense. He has decided to harvest 10 plots and use this information to estimate the total yield. Based on this estimate, he will decide whether to harvest the remaining plots.

Convenience Sample The farmer decided to harvest the 10 easiest plots to harvest. He then had second thoughts and decided to hire you, a statistics student, somewhat knowledgeable about these matters but far cheaper than a statistician. You are still to choose 10 plots but try different sampling methods to determine which one will give the best estimate of the actual yield. X X X X X X X X X X River

Simple Random Sample Use a random number table to select 10 plots. Describe the method used and mark the plots. River

Stratified Sample (vertical) Determine a method that will allow you to choose one box in each column. Describe the method and select the plots River

Stratified Sample (horizontal) Determine a method that will allow you to choose one box in each row. Describe the method and select the plots River

Determining best method The table below represents the yield per plot. You will need this to determine which method is best and why

Determining best method MethodMean yield per plot Estimated Total yield Convenience sample Simple Random sample Vertical strata Horizontal strata

Observations 1)You looked at four different methods of choosing plots. Is there a reason, other than convenience, to choose one method over another? 2)How did your estimates vary according to the different sampling methods used?

Observations 3) Which sampling method should you use? 4) What was the actual yield of the farmers field

Part two The farmer was very impressed with your results and seeks to improve the yield of his field the following year. Believing that the river does impact the yield he has installed an irrigation system. He now needs you to determine if the system truly has had an impact by having you do a simple random sample, a vertical strata and a horizontal strata then calculate the results and compare.

Simple Random Sample Start at the row of the random number table which = 3 times your team number Describe the method used and mark the plots. River

Stratified Sample (vertical) Continuing after the last number used. Determine a method that will allow you to choose one box in each column. Describe the method and select the plots River

Stratified Sample (horizontal) Continuing from the last number you used. Determine a method that will allow you to choose one box in each row. Describe the method and select the plots River

Results after irrigation Using the data below, calculate the mean yield per plot and the total estimated yield

Determining best method MethodMean yield per plot Estimated Total yield Simple Random sample Vertical strata Horizontal strata

Results after irrigation Place your results in the row corresponding to your calculator number using the link below. River Project Spreadsheet Once everyone has entered their data, create a boxplot for each type. Boxplots must be created to scale and should be one below the other.

Observations part 2 1)Compare the boxplots of the sample yield, for the entire field what do you notice?

Observations part 2 2) Does it make sense to use one method over another and why?