Since P-value (0.3199) is not less than (0.05), fail to reject the . There is insufficient evidence α to support the recalibration of the machine can lower the standard deviation. Example 2: Data obtained from the National Center for Health Statistics show that men between the ages of 20 to 29 have a mean height of 69.3 inches, with a standard deviation of 2.9 inches. A baseball analyst wonders whether the standard deviation of heights of major-league baseball is less than 2.9 inches. The heights (in inches) of 20 randomly selected players are shown below. = 69.3 = 2.9 = 20 µ s n 72 74 71 72 76 70 77 75 72 72 77 72 75 70 73 73 75 73 74 74 (a) Verify the data are normally distributed by drawing a normal probability plot. Open StatCrunch Input raw data Graph QQ Plot var1 Compute → → → → → The sample data are close to the straight line. Thus, the data may have come from a population that is normally distributed. (b) Use StatCrunch to compute the sample standard deviation. Open StatCrunch Stat Calculators Summary Statistics column var1 Statistics: → → → → → → Variance Compute → (c) Test the notion at the level of significance. = 69.3 = 2.9 = 20 = 73.35 = 2.0589982 µ n Setup: : = 2.9 : < 2.9
Since P-value (0.3199) is not less than α (0.05), fail to reject the . There is insufficient evidence to support the recalibration of the machine can lower the standard deviation. Example 2: Data obtained from the National Center for Health Statistics show that men between the ages of 20 to 29 have a mean height of 69.3 inches, with a standard deviation of 2.9 inches. A baseball analyst wonders whether the standard deviation of heights of major-league baseball is less than 2.9 inches. The heights (in inches) of 20 randomly selected players are shown below. µ = 69.3 s = 2.9 n = 20 72 74 71 72 76 70 77 75 72 72 77 72 75 70 73 73 75 73 74 74 (a) Verify the data are normally distributed by drawing a normal probability plot. Open StatCrunch → Input raw data → Graph → QQ Plot → var1 → Compute The sample data are close to the straight line. Thus, the data may have come from a population that is normally distributed. (b) Use StatCrunch to compute the sample standard deviation. Open StatCrunch → Stat → Calculators → Summary Statistics → column → var1 → Statistics: Variance → Compute (c) Test the notion at the level of significance. µ = 69.3 = 2.9 n = 20 = 73.35 = 2.0589982 Setup: : = 2.9 : < 2.9