Statistics Cheat Sheet

2141 WordsMar 4, 20159 Pages
What proportion of a normal distribution is located in the tail beyond z = +2.00? 0.0228 What proportion of a normal distribution is located between the mean and z = 1.40? 0.4192 The Z-score corresponding to the 52nd percentile is .05 A normally distributed variable has a mean of 10 and a standard deviation of 2. The probability that a value between 7 and 9 is obtained is .2417 An accelerated life test on a large number of type-D alkaline batteries revealed that the mean life for a particular use before they failed is 19.0 hours. The distribution of the lives approximated a normal distribution. The standard deviation was 1.2 hours. About 95.44% of the batteries failed between what two values? 16.6 & 21.4 The average time students need…show more content…
n = 100 with s^2 = 100 I other factors are held constant, which set of characteristics is most likely to produce a significant t statistic? n = 50 with s^2 = 50 If other factors are held constant, what is the effect of increasing the sample size? It will decrease the estimated standard error and increase the likelihood of rejecting H0 A researcher conducts a one-sample hypothesis test using a sample of n = 40 from an unknown population. What is the df value for the t statistic? 39 With α= 0.05, what is the critical t value for a one-tailed test with n = 15? t = 1.761 With α= 0.05 and df = 20, the critical values for a two-tailed t test are t = +-2.086. Assuming all other factors are held constant, if the df value were decreased to df = 10, what would happen to the critical values for t? They would increase (move farther from zero). A sample of n = 4 scores is selected from a population with an unknown mean. The sample has a mean of M = 40 and a variance of s2= 16. Which of the following is the correct 90% confidence interval for μ? μ= 40 +-2.353(2) When is it appropriate to use the two sample, pooled variance t-test? When 2 independent samples are compared. Which of the following accurately describes an independent-measures study? It uses a different group of participants for each of the treatment conditions being compared. Which of the following is the correct null hypothesis for an independent-measures t test? Mu1-Mu2 = 0 Accounting procedures allow a
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