stats quiz 1
what is the different between a random sample and a simple random sample?
In a random sample, every member of the population has an equal chance of being selected. In a simple random sample, every possible sample of the same size has an equal chance of being selected.
a pharmaceutical company wants to test the effectiveness of a new allergy drug. The company identifies 250 females ages 30 to 35 who suffer from severe allergies. The subjects are randomly assigned into two groups. One group is fiven the drug and the other is given a placebo that looks exactly like the drug. After six months, the subjects' symptoms are studied and compared. a) identify the experimental units and treatments used b) identify a potential problem with the experimental design being used and suggest a way to improve it c) how could this experiment be designed to be double-blind?
a) experimental units are the 250 females ages 30 to 35 and the treatment is a new allergy drug b) it may be bias if the researchers know which subjects took the drug. that could be eliminated by a double blind c) a way to make it a double blind is to make the researchers not know which patients received the real drug or placebo
what is the difference between an observational study and an experiment?
an experiment has a treatment applied to part of a population and the responses are observed. an observational study measures characteristics of interest of part of a population but does not change existing conditions.
identify the sampling technique used and discuss the potential source of bias if any: questioning students as they leave a university library, a researcher asks 358 students about their drinking habits
convenience sampling is used because the students are chosen due to their convenience of location. bias may enter into the sample because the students sampled may not be representative of the population of students.
determine whether the study is an experiment or an observational study: to study the effect of music on driving habits, eight drivers (four male and four female) drove 500 miles while listening to different genres of music.
experiment since a treatment is applied
determine the level of measurement of temperature
interval
determine the level of measurement of the data set: the years that a television show on ABC won the best comedy series EMMY
interval
determine the level of measurement of allergies
nominal
determine the level of measurement of the data set: the jersey numbers for players on a soccer team
nominal
determine the level of measurement of pain level on a scale of 1-10
ordinal
determine the level of measurement of the data set: the top five fiction books on the new york times best sellers list
ordinal
determine whether the numerical value is a parameter or a statistic: sixty two of the 97 passengers aboard the Hindenburg airship survived its explosion
parameter
identify the population and sample: a survey of 12,082 US adults found that 45.5% received an influenza vaccine for a recent flu season
population: all US adults sample: 12,082 US adults
identify the population and sample: a survey of 55 US law firms found that the average hourly billing rate was $425
population: all US law firms sample: 55 US law firms
identify the population and sample: a survey of 202 pilots found that 20% admit that they have made a serious error due to sleepiness
population: all pilots sample: 202 pilots surveyed
identify the population and sample: a survey of 1015 US adults found that 32% have had to put off medical care for themselves or their family in the past year due to the cost
population: all us adults sample: 1015 US adults
determine if the data is qualitative or quantitative: eye colors of models
qualitative
determine whether the data set is quantitative or qualitative and the level of measurement: the regions representing the top sales people in a corporation for the past six years listed
qualitative, nominal
determine whether the data set is quantitative or qualitative and the level of measurement: the top five musical albums for 2012
qualitative, ordinal
determine whether the data set is quantitative or qualitative and the level of measurement: the top five teams in college football poll
qualitative, ordinal
determine if the data is qualitative or quantitative: weights of infants at a hospital
quantitative
determine whether the data is qualitative or quantitative: heights of hot air balloons
quantitative
determine the level of measurement of weight
ratio
identify the sampling technique used and discuss the potential source of bias if any: chosen at random, 580 customers at a car dealership are contacted and asked their opinions of the service they received
simple random sampling is used because each customer has an equal chance of being contacted, and all samples of 580 customers have an equal chance of being selected
identify the sampling technique used and discuss the potential source of bias if any: using a random digit dialing, researchers call 1400 people and ask what obstacles (such as childcare) keep them from exercising
simple random sampling is used because each telephone number has an equal chance of being dialed, and all samples of 1400 phone numbers have an equal chance of being selected. the sample may be biased because telephone sampling only samples individuals with telephones who are available and are willing to respond.
determine whether the numerical value is a parameter or a statistic: In a survey of 300 computer users, 8% said their computers had malfunctions that needed to be repaired by service technicians
statistic
determine whether the numerical value is a parameter or a statistic: a survey of 1004 US adults found that 52% think China's emergence as a world power is a major threat to the well-being of the United States.
statistic
determine whether the numerical value is a parameter or a statistic: the average annual salary for 35 of a company's 1200 accountants is $68,000.
statistic
identify the sampling technique used and discuss the potential source of bias if any: soybeans are planted on a 48 acre field. the field is divided into one acre subplots. a sample is taken from each subplot to estimate the harvest.
stratified sampling is used because a sample is taken from each one acre subplot