A chemical engineer desiring to study the evaporation rate of water from brine evaporation beds obtained data on the number of inches of evaporation in each of 55 July days spread over 4 years. The data are given in the following stem and leaf plot, which shows that the smallest data value was .02 inches, and the largest .56 inches. .0 2, 6 .1 1, 4 .2 1, 1, 1, 3, 3, 4, 5, 5, 5, 6, 9 .3 0, 0, 2, 2, 2, 3, 3, 3, 3, 4, 4, 5, 5, 5, 6, 6, 7, 8, 9 .4 0, 1, 2, 2, 2, 3, 4, 4, 4, 5, 5, 5, 7, 8, 8, 8, 9, 9 .5 2, 5, 6 Find the (a) sample mean; (b) sample median; (c) sample standard deviation of these data. (d) Do the data appear to be approximately normal? (e) What percentage of data values are within 1 standard deviation of the mean?

Stat 461: Week 1 Notes Principles of Experimental Design 1. What is being assumed 2. Nuisance/Noise Factors (aka Confounding Variables) a. Def: factors other than one being studied which could alter the experiment (ex: if you’re seeing what type of fertilizer is best for a crop confound variables could be the soil; if two crops have two different soil types and two different fertilizer types the crop yield may be larger/smaller due to the soil and not the fertilizer) b. Statistical Model- the difference between the mean of the data and one piece of data is due to confounding variables ( = + = mean plus confounding