Intro to Stat 1.4
A professor wants to randomly select 4 students to go to the board. She decides to randomly select the third student who enters the classroom and every sixth student after that. Determine the students who will be going to the board. Write down the student numbers.
3, 9, 15, 21
The human resource department at a certain company wants to conduct a survey regarding worker benefits. The department has an alphabetical list of all 8266 employees at the company and wants to conduct a systematic sample of size 70. Determine the individuals who will be administered the survey. Randomly select a number from 1 to k. Suppose that we randomly select 5. Starting with the first individual selected, the individuals in the survey will be
5, 123, 241,.... 8147
When obtaining a stratified sample, the number of individuals included within each stratum must be equal. (T/F)
False. Within stratified samples, the number of individuals sampled from each stratum should be proportional to the size of the strata in the population.
To determine customer opinion of their safety features, Toyota randomly selects 70 dealerships during a certain week and surveys all customers visiting the dealerships. What type of sampling is used?
Cluster
A(n) _________ sample is obtained by dividing the population into groups and selecting all individuals from within a random sample of the groups
Cluster
A _______ is obtained by selecting all individuals within a randomly selected collection or group of individuals.
Cluster sample
A radio station asks its listeners to call in their opinion regarding the use of pesticides in residential areas. What type of sampling is used?
Convenience
In a _____ sample, the individuals are easily obtained and not based on randomness. (Self-selected)
Convenience
How to obtain a cluster sample using StatCrunch
Data > Simulate > Discrete Uniform
How to obtain a stratified sample using StatCrunch
Data > Simulate > Discrete Uniform > Use Dynamic Seed
Toshiba wants to administer a satisfaction survey to its current customers. Using their customer database, the company randomly selects 80 customers and asks them about their level of satisfaction with the company. What type of sampling is used? What kind of sample is it when you choose a random sample from the population?
Simple Random
To determine her body temperature, Charlotte divides up her day into three parts: morning, afternoon, and evening. She then measures her body temperature at 3 randomly selected times during each part of the day. What type of sampling is used?
Stratified
A __________ is obtained by dividing the population into nonoverlapping groups called strata and then obtaining a simple random sample from each stratum. The individuals within each stratum should be homogenous (similar) in some way
Stratified sample
To estimate the percentage of defects in a recent manufacturing batch, a quality control manager at Microsoft selects every 14th software CD that comes off the assembly line starting with the fifth until she obtains a sample of 60 software CDs. What type of sampling is used?
Systematic
A ________ is obtained by selecting every kth individual from the population. The first individual selected corresponds to a number between 1 and k
Systematic sample
In both simple random sampling and stratified sampling, a frame must exist. Therefore, these sampling techniques require some preliminary work before the sample can be found. A sampling technique that does not require a frame is ____________.
Systematic sampling
The human resource department at a certain company wants to conduct a survey regarding worker benefits. The department has an alphabetical list of all 8266 employees at the company and wants to conduct a systematic sample of size 70. What is K?
k = 118
To determine her body temperature, Charlotte divides up her day into three parts: morning, afternoon, and evening. She then measures her body temperature at 3 randomly selected times during each part of the day. What is k?
k = 118
Suppose the size of a population is N=6500 and the sample size desired is n=17. What value of k should be used to obtain a systematic sample from this population?
k = 382
