Intro to Stat Chapter 1 Quiz Notes (For Chapters 1 & 2 Exam)
Determine whether the variable is qualitative or quantitative. Goals scored in a hockey game. Is the variable qualitative or quantitative?
The variable is quantitative because it is a numerical measure.
A polling organization contacts 2499 adult men who are 40 to 60 years of age and live in the United States and asks whether or not they had seen their family doctor within the past 6 months. What is the population in the study? What is the sample in the study?
- Adult men who are 40 to 60 years of age and live in the United States. - The 2499 adult men who are 40 to 60 years of age and live in the United States.
The manager of a shopping mall wishes to expand the number of shops available in the food court. She has a market researcher survey the first 100 customers who come into the food court during weekend evenings to determine what types of food the shoppers would like to see added to the food court. Complete parts (a) and (b) below. (a) The survey has bias. Determine whether the flaw is due to the sampling method or the survey itself. For biased surveys, identify the cause of the error. What is the cause of the bias? (b) Suggest a remedy to the problem. Which of the following is the best way to remedy this problem?
- Sampling bias - Ask customers throughout the day on both weekdays and weekends.
The survey has bias. (a) Determine the type of bias. (b) Suggest a remedy. A polling organization conducts a study to estimate the percentage of households that have Internet access. It mails a questionnaire to 1894 randomly selected households across the country and asks the head of each household if he or she has Internet access. Of the 1894 households selected, 26 responded. (a) Which of these best describes the bias in the survey? (b) How can the bias be remedied?
-Nonresponse bias -The polling organization should try contacting households that do not respond by phone or face-to-face.
What is a closed question? What is an open question? Discuss the advantages and disadvantages of each type of question. What is a closed question? What is an open question?
A closed question has fixed choices for answers, whereas an open question is a free-response question.
Which allows the researcher to claim causation between an explanatory variable and a response variable?
A designed experiment allows the researcher to claim causation between an explanatory variable and a response variable.
What is an observational study? What is a designed experiment? Which allows the researcher to claim causation between an explanatory variable and a response variable? What is a designed experiment?
A designed experiment is when a researcher assigns individuals to a certain group, intentionally changing the value of an explanatory variable, and then recording the value of the response variable for each group.
What does it mean when a part of the population is under-represented?
A part of the population is under-represented when it is proportionally smaller in a sample than in its population.
What is an observational study? What is a designed experiment? Which allows the researcher to claim causation between an explanatory variable and a response variable? What is an observational study?
An observational study measures the value of the response variable without attempting to influence the value of either the response or explanatory variables.
What is a closed question? What is an open question? Discuss the advantages and disadvantages of each type of question. Discuss the advantages and disadvantages of each type of question.
Closed questions are easier to analyze but limit the responses. Open questions allow respondents to state exactly how they feel but are harder to analyze due to the variety of answers and possible misinterpretation of answers.
To determine customer opinion of their pricing, Greyhound Lines randomly selects 100 busses during a certain week and surveys all passengers on the busses. What type of sampling is used?
Cluster
Determine whether the following statement is true or false. Explain. When obtaining a stratified sample, the number of individuals included within each stratum must be equal.
False. Within stratified samples, the number of individuals sampled from each stratum should be proportional to the size of the strata in the population.
Explain the difference between a single-blind and a double-blind experiment.
In a single-blind experiment, the subject does not know which treatment is received. In a double-blind experiment, neither the subject nor the researcher in contact with the subject knows which treatment is received.
Determine whether the underlined numerical value is a parameter or a statistic. Explain your reasoning. A certain zoo found that 8% of its 843 animals were nocturnal.
Parameter, because the data set of all 843 animals in a zoo is a population.
Determine the level of measurement of the variable. Favorite color
Nominal
Determine whether the underlined value is a parameter or a statistic. In a survey of 1,011 people aged 50 or older, 73% agreed with the statement "I believe in life after death." Is the value a parameter or a statistic?
The value is a statistic because the 1,011 people age 50 or older are a sample.
What is replication in an experiment?
Replication is applying each treatment to more than one experimental unit.
Define statistics.
Statistics is the science of collecting, organizing, summarizing, and analyzing information to draw a conclusion and answer questions. In addition, statistics is about providing a measure of confidence in any conclusions.
Determine whether the study depicts an observational study or an experiment. Fifty patients on dialysis are divided into two groups. One group receives an experimental drug to fight cancer, the other a placebo. After two years, kidney functionality is measured. Does the description correspond to an observational study or an experiment?
The study is an experiment because the researchers control one variable to determine the effect on the response variable.
Determine whether the study depicts an observational study or an experiment. Obese adults are randomly divided into two groups. One group replaces one meal a day with vegetables. the other does cardio for 30 minutes a day. After 3 months, each group is weighed to compare weight loss.
The study is an experiment because the researchers control one variable to determine the effect on the response variable.
Researchers wanted to test the effectiveness of a new drug therapy for treating patients with multiple sclerosis. To do this, they identified 60 patients with a diagnosis of multiple sclerosis. Patients were randomly assigned to one of three treatment groups. Twenty patients were randomly assigned to receive the new drug therapy, another 20 received the older drug therapy, and the final 20 received a placebo therapy. To measure the effectiveness of the treatment, researchers scored each patient on a standardized rating scale for multiple sclerosis. After collecting and comparing the scores for the three treatment groups, the researchers concluded that the new drug therapy is significantly more effective than both the older drug therapy and the placebo therapy in the treatment of multiple sclerosis. Complete parts (a) through (f).
(a) What type of experimental design is this? - Completely randomized design (b) What is the population being studied? All patients with a diagnosis of multiple sclerosis. (c) What is the response variable in this study? The score on the standardized rating scale for multiple sclerosis. (d) What are the treatment(s)? The new drug therapy, the older drug therapy, and the placebo therapy (e) Identify the experimental units. Choose the correct answer below. The 60 patients with a diagnosis of multiple sclerosis. (f) Which figure illustrates the design of this experiment? Figure 1
Determine whether the following statement is true or false. Explain. Inferences based on voluntary response samples are generally not reliable.
True, because it is often the case that the individuals who volunteer do not accurately represent the population.