Chapter 1 Summary, Review, & Quiz
A pharmaceutical company wants to conduct a survey of 30 individuals who have high cholesterol. The company has obtained a list from primary care physicians throughout the country of 7200 individuals who are known to have high cholesterol. Design a sampling method to obtain the individuals in the sample. Be sure to support the choice.
-Group the individuals by common primary care physician. For each group, assign all the individuals different numbers, and use a random number table to select an appropriate number of individuals. -Group the individuals by common primary care physician. Assign each physician a different number and use a random number table to select physicians until the total number of patients of all the selected physicians is at least 30. -Alphabetize the list of 7200 individuals by last name and select one of the first 240 individuals at random. Starting from the selected individual, read down the list and select every 240th individual.
discrete or continuous: number of points scored in a baseball game
-discrete because it is countable
designing an experiment steps...
1. identify the problem to be solved 2. determine the factors that affect the response variable 3. determine the number of experimental units 4. determine the level of each factor 5. conduct the experiment 6. test the claim
a salesperson obtained a systematic sample size of 30 from a list of 600 clients. to do so, he randomly selected a number from 1 to 20, obtaining the number 11. he included in the sample the 11th client on the list & every 20th client thereafter. list the numbers that correspond to the 30 clients selected.
11, 31, ...., 591 >11 + (30-1)20
distinguish between nonsampling error and sampling error.
Nonsampling error is the error that results from undercoverage, nonresponse bias, response bias, or data-entry errors. Sampling error is the error that results because a sample is being used to estimate information about a population.
A golf pro wanted to compare two types of golf clubs. One type is graphite-shafted and the other is steel-shafted. It is a common belief that graphite shafts give more distance. This belief is tested by having 10 golfers hit one ball with each type of club and then determining the distance that the ball traveled. A coin flip was used to determine which type of club each player would hit with first. Results indicated that there was no difference in the two types of club. Complete parts (a) through (f) below.
a. What type of experimental design is this? matched-pairs design b. what is the response variable in this study? the distance c. what is the factor that is set to predetermined levels? what is the treatment? the factor is the type of club. the treatments are graphite-shafted & steel-shafted d. identify the experimental units. the golfers e. why is a coin used to decide the club each player would hit with first? to eliminate bias as to which club was used first f. draw a diagram to illustrate the design. figure 2
The survey has bias. (a) Determine the type of bias. (b) Suggest a remedy. An anti-free trade advocate wants to estimate the percentage of people who favor increasing tariffs on imported goods. He conducts a nationwide survey of 1440 randomly selected adults 18 years and older. The interviewer asks the respondents, "Do you favor supporting local business with tariffs?"
a. response bias b. the interviewer should reword the question
A physician wanted to compare two types of headache relief. One type is medication and the other is using pressure points. It is a common belief that medication relieves pain faster. This belief is tested by having 10 migraine sufferers compare both types of pain relief and record their observations on a standardized scale of response. A coin flip was used to determine which type of headache relief each individual would try first. Results indicated that there was no difference in the two types of pain relief.
a. what type of experimental design is this? matched-pairs design b. what is the response variable in this study? the recorded observations c. what is the factor that is set to predetermined levels? what is the treatment? The factor is the type of pain relief. The treatments are medication and using pressure points. d. Identify the experimental units. the migraine sufferers e. Why is a coin used to decide the headache relief each individual would try first? To eliminate bias as to which pain relief was used first f. figure 2
researchers wanted to determine if there was an association between daily cantaloupe consumption & the occurrence of heart disease. the researchers looked at 94,872 women & asked them to report their cantaloupe-eating habits. the researchers also determined which of the woman had congestive heart failure. after their analysis, the researchers concluded that the consumption of two or more servings of cantaloupe per day was associated with a reduction in congestive heart failure. complete parts a through c.
a. what type of observational study was this? this was a cross sectional study because all information about the individuals was collected at a specific point in time b. what is the response variable in the study? is the response variable qualitative or quantitative? what is the explanatory variable? the response variable is whether the woman has congestive heart failure or not. The response variable is qualitative. The explanatory variable is the consumption of cantaloupe c. ...why was it important to adjust for these variables? the researchers may be concerned with confounding that occurs when the effects of two or more explanatory variables are not separated or when there are some explanatory variable that were not considered in a study, but that affect the value of the response variable.
In an effort to determine the ability of chewing gum to remove stains on teeth, researchers conducted an experiment in which 64 bovine incisors (teeth) were stained with natural pigments such as coffee for 10 days. Each tooth was randomly assigned to one of four treatments: gum A, gum B, gum C, or saliva. Each tooth group was placed into a device that simulated a human chewing gum. The temperature of the device was maintained at body temperature and the tooth was in the device for 20 minutes. The process was repeated six times (for a total of 120 minutes of chewing). The researcher conducting the experiment did not know which treatment was being applied to each experimental unit. Upon removing a tooth from the chewing apparatus, the color change was measured. The percentage of stain removed by each treatment after 120 minutes is given in the table. The researchers concluded that gums A and B removed significantly more stain than gum C or saliva. In addition, gum C removed significantly more stain than saliva.
a. what type of study is this? completely-randomized design b. what are the treatments in the study? the type of gum or saliva c. how many levels of treatment are in the study? 4 d. what is the response variable in this study? percentage of stain removed e. which of the following were factors that were fixed at one level in this study? Select all that apply. -the temperature of the chewing device | the amount of chewing f. identify the experimental units. the 64 bovine incisors
To determine customer opinion of their inflight service, Continental Airlines randomly selects 150 flights during a certain week and surveys all passengers on the flights. what type of sampling is used?
cluster
determine the type of sampling used: An Internet service provider randomly selects 15 residential blocks from a large city and surveys every household in these 15 blocks to determine whether they use a high-speed Internet service, or not.
cluster sample
discrete or continuous: running time of a film
continuous because it is countable
determine the type of sampling used: On election day, a pollster positions herself outside a polling place near her home and asks the first 50 voters leaving the facility to complete a survey.
convenience sample
Determine the level of measurement of the following variable: birth year
interval
level of measurement: monthly temperatures, 65 degrees, 69 degrees, 73 degrees, 77 degrees, and 81 degrees
interval
Determine the level of measurement of the following variable: marital status
nominal
Determine the level of measurement of the following variable: Stock rating (strong buy, buy, hold, sell, strong sell)
ordinal
Determine whether the underlined numerical value is a parameter or a statistic: In a certain soccer league, 43% of the 14 teams had won more games than they had lost.
parameter, because the data set of all 14 teams is a population
Brand name of a pair of running shoes: quantitative or qualitative?
qualitative
Weight in carats of an uncut diamond: quantitative or qualitative?
quantitative - continuous
Number of new automobiles sold at a dealership on a given day: quantitative or qualitative?
quantitative - discrete
qualitative or quantitative: time to swim 100 meters
quantitative because it is a numerical measure
Determine the level of measurement of the following variable: number of siblings
ratio
parameter or statistic: in a nation survey on substance abuse, 66.4% of respondents who were full-time college students aged 18 to 22 reported using alcohol within the past month.
statistic because the respondents who were full-time college students aged 18 to 22 are a sample
To determine her blood sugar level, Carrie divides up her day into three parts: morning, afternoon, and evening. She then measures her blood sugar level at 2 randomly selected times during each part of the day. what type of sampling is used?
stratified
determine the type of sampling used: Thirty-five sophomores, 22 juniors, and 35 seniors are randomly selected to participate in a study from 574 sophomores, 462 juniors, and 532 seniors at a certain high school.
stratified sample
determine the type of sampling used: Officers for the Department of Motor Vehicles pull aside every 40th tractor trailer passing through a weigh station, starting with the 12th, for an emissions test.
systematic sample
