The article "Wastewater Treatment Sludge as a Raw Material for the Production of Bacillus tluiringiensis Based Biopesticides" (M. Tirado Montiel. R. Tyagi, and J. Valero. Water Research, 2001: 3807-3816) presents measurements of total solids, in g/L. for seven sludge specimens. The results (rounded to the nearest gram) are 20, 5, 25, 43, 24, 21, and 32. Assume the distribution of total solids is approximately symmetric.

a.Can you conclude that the mean concentration of total solids is greater than 14 g/L? Compute the appropriate test statistic and find the P-value.

b.Can you conclude that the mean concentration of total solids is less than 30 g/L? Compute the appropriate test statistic and find the P-value.

c.An environmental engineer claims that the mean concentration of total solids is equal to 18 g/L. Can you conclude that the claim is false?

PSYCH STATS POWERPOINT 3 ● percentile is a score that is used to determine the percentile rank ● central tendency: single score chosen to represent the entire set of scores ○ defines the center of distribution ○ allows you to compare 2 sets of data ● problems… its a single score ○ no standard procedure to calculate ○ not all distributions are the same ■ some aren’t symmetrical and this makes it more difficult to determine the best value to be representative of the sample ● the mean: the average ● median: middle value ● mode: most common value Mode ● calculated by looking at the most common value ● taken straight from the scores ● best used for nominal data ● if two values occ