- 7-2.1: What are the properties of the t distribution?
- 7-2.2: What is meant by degrees of freedom?
- 7-2.3: When should the t distribution be used to find a confidence interva...
- 7-2.4: (ans) Find the values for each. a. ta_2 and n _ 18 for the 99% conf...
- 7-2.5: Visits to Networking Sites A sample of 10 networking sites for a sp...
- 7-2.6: Digital Camera Prices The prices (in dollars) for a particular mode...
- 7-2.7: Women Representatives in State Legislature Astate representative wi...
- 7-2.8: State Gasoline Taxes Arandom sample of state gasoline taxes (in cen...
- 7-2.9: Workplace Homicides A sample of six recent years had an average of ...
- 7-2.10: Dance Company Students The number of students who belong to the dan...
- 7-2.11: Distance Traveled to Work A recent study of 28 employees of XYZ com...
- 7-2.12: Thunderstorm Speeds Ameteorologist who sampled 13 thunderstorms fou...
- 7-2.13: Students perTeacher in U.S. Public Schools The national average for...
- 7-2.14: Social Networking Sites A recent survey of 8 social networking site...
- 7-2.15: Chicago Commuters Asample of 14 commuters in Chicago showed the ave...
- 7-2.16: Hospital Noise Levels For a sample of 24 operating rooms taken in t...
- 7-2.17: Costs for a 30-Second Spot on Cable Television The approximate cost...
- 7-2.18: Football Player Heart Rates For a group of 22 college football play...
- 7-2.19: Grooming Times for Men and Women It has been reported that 20- to 2...
- 7-2.20: Unhealthy Days in Cities The number of unhealthy days based on the ...
- 7-2.21: A one-sided confidence interval can be found for a mean by using wh...
Solutions for Chapter 7-2: Confidence Intervals for the Mean When s Is Unknown
Full solutions for Elementary Statistics: A Step by Step Approach 8th ed. | 8th Edition
2 k factorial experiment.
A full factorial experiment with k factors and all factors tested at only two levels (settings) each.
a-error (or a-risk)
In hypothesis testing, an error incurred by failing to reject a null hypothesis when it is actually false (also called a type II error).
A study in which a sample from a population is used to make inference to a future population. Stability needs to be assumed. See Enumerative study
An attribute control chart that plots the total number of defects per unit in a subgroup. Similar to a defects-per-unit or U chart.
Central composite design (CCD)
A second-order response surface design in k variables consisting of a two-level factorial, 2k axial runs, and one or more center points. The two-level factorial portion of a CCD can be a fractional factorial design when k is large. The CCD is the most widely used design for itting a second-order model.
A correction factor used to improve the approximation to binomial probabilities from a normal distribution.
A graphical display used to monitor a process. It usually consists of a horizontal center line corresponding to the in-control value of the parameter that is being monitored and lower and upper control limits. The control limits are determined by statistical criteria and are not arbitrary, nor are they related to speciication limits. If sample points fall within the control limits, the process is said to be in-control, or free from assignable causes. Points beyond the control limits indicate an out-of-control process; that is, assignable causes are likely present. This signals the need to ind and remove the assignable causes.
Defect concentration diagram
A quality tool that graphically shows the location of defects on a part or in a process.
Defects-per-unit control chart
See U chart
A subset of effects in a fractional factorial design that deine the aliases in the design.
W. Edwards Deming (1900–1993) was a leader in the use of statistical quality control.
Discrete uniform random variable
A discrete random variable with a inite range and constant probability mass function.
A concept in parameter estimation that uses the variances of different estimators; essentially, an estimator is more eficient than another estimator if it has smaller variance. When estimators are biased, the concept requires modiication.
Estimator (or point estimator)
A procedure for producing an estimate of a parameter of interest. An estimator is usually a function of only sample data values, and when these data values are available, it results in an estimate of the parameter of interest.
Extra sum of squares method
A method used in regression analysis to conduct a hypothesis test for the additional contribution of one or more variables to a model.
Finite population correction factor
A term in the formula for the variance of a hypergeometric random variable.
Fixed factor (or fixed effect).
In analysis of variance, a factor or effect is considered ixed if all the levels of interest for that factor are included in the experiment. Conclusions are then valid about this set of levels only, although when the factor is quantitative, it is customary to it a model to the data for interpolating between these levels.
Fraction defective control chart
See P chart
The geometric mean of a set of n positive data values is the nth root of the product of the data values; that is, g x i n i n = ( ) = / w 1 1 .
The harmonic mean of a set of data values is the reciprocal of the arithmetic mean of the reciprocals of the data values; that is, h n x i n i = ? ? ? ? ? = ? ? 1 1 1 1 g .