Ch. 1 - Data and Statistics

A study took a group of adults and randomly divided them into two groups. One group was told to drink tea every night for a week, while the other group was told not to drink tea that week. Researchers then compared when each group fell asleep.Which type of study method is this? A. Experimental study B. Observational study C. Existing sources

A. Experimental study

Elements

- the entities on which data are collected

Data

- the facts and figures collected, analyzed, and summarized for presentation and interpretation

Numerical Summary

- the most common numerical descriptive statistic is the mean (or average)

Statistical Interference

- the process of using data obtained from a sample to make estimates and test hypotheses about the characteristics of a population

Population

- the set of all elements of interest in a particular study

Which of the following is NOT an example of descriptive statistics? a. A histogram depicting the age distribution for 30 randomly selected students b. An estimate of the number of Alaska residents who have visited Canada c. A table summarizing the data collected in a sample of new-car buyers d. The proportion of mailed-out questionnaires that were returned

b. An estimate of the number of Alaska residents who have visited Canada

Statistics is the art and science of collecting, analyzing, presenting, and interpreting data. A. True B. False

A. True

Which of the following is a categorical variable? A. Your age on your last birthday B. Your cell phone area code C. Your accounting class start time D. Your high school graduation year

B. Your cell phone area code

Which of the following variables uses the interval scale of measurement? a. Standardized test score b. Time duration c. Student ID number d. Vehicle miles-per-gallon

a. Standardized test score

How do you find the total number of data values in a complete data set?

the # of elements X the # of variables

Which of the following variables use the ratio scale of measurement? a. Social security number b. Temperature c. Gender d. Income

d. Income

In a sample of 400 students in a university, 80 or 20% are Business majors. Based on the above information, the school's paper reported that "20% of all the students at the university are Business majors." This report is an example of: a. a census b. descriptive statistics c. an experiment d. statistical inference

d. statistical inference

What are the 4 kinds of Scales of Measurement to obtain data for a particular variable?

- Nominal Scale - Ordinal Scale - Interval Scale - Ratio Scale

Variable

- a characteristic of interest for the elements

The principal of a large high school is considering adopting a dress code for the upcoming school years. Before going to the school board, he wants to know the percentage of parents who would favor a dress code. He randomly chooses 115 parents to interview. Out of the 115 parents surveyed, 76% favor a dress code. 1. Identify the population of interest 2. Describe the sample.

1. All parents of the high school students 2. The 115 parents surveyed

A student worked on her statistics project in the library and found a reference book that contained the median family incomes for all 50 states. On her project, she would report her data as being collected ________. A. from an existing source B. from an experimental study C. observationally D. from a survey

A. from an existing source

Parking at a university has become a problem. University administrators are interested in determining the average time it takes a student to find a parking spot. An administrator inconspicuously followed 120 students and recorded how long it took each of them to find a parking spot. Identify the population of interest to the university administration. A. the entire set of students who park at the university B. the 120 students about whom the data were collected C. the entire set of faculty, staff, and students who park at the university D. the students who park at the university between 9 and 10 AM on Wednesdays

A. the entire set of students who park at the university

In a sample of 1,600 registered voters, 912 or 57% approve of the way the President is doing his job. A political pollster estimates: "Fifty-seven percent of all voters approve of the President." This statement is an example of A. a census B. descriptive statistics C. an experiment D. statistical inference

D. statistical inference

Identify each of the following variables as categorical or quantitative. a. Political party affiliations b. Weights of the football team members c. Number of children in a household d. Type of car you drive

a. categorical b. quantitative c. quantitative d. categorical

In a post office, the mailboxes are numbered from 1 to 4,500. These numbers represent: a. categorical data. b. quantitative data. c. either categorical or quantitative data. d. since the numbers are sequential, the data is quantitative.

a. categorical data. You cannot perform meaningful operations with the data such as, adding or subtracting

Some hotels ask their guests to rate the hotel's services as excellent, very good, good, and poor. This is an example of the: a. ordinal scale. b. ratio scale. c. nominal scale. d. interval scale.

a. ordinal scale.

Observational (Non-experimental) Studies

- no attempt is made to control or influence the variables of interest - ex: survey

Descriptive Statistics

- numerical data used to measure and describe characteristics of groups - tabular, graphical, and numerical summaries of data

Experimental Studies

- perform an experiment by applying a treatment to part of a population and observing responses

Statistics

- the art and science of collecting, analyzing, presenting, and interpreting data

Are these examples of descriptive or inferential statistics? - In a survey, 359 college students were asked if they had tried Vanilla Coke. Among the respondents 83% said yes. - In a survey, 359 college students were asked if they had tried Vanilla Coke. Among the respondents 83% said yes. It is reported that about 83% of all college students have tried Vanilla Coke.

- Descriptive; The results of the sample are described without making any generalizations about the population. - Inferential; The results of the sample are extended to make a generalization about the population.

Ordinal Scale

- a scale of measurement in which the measurement categories form a rank order along a continuum - ex: Military Rank, Degrees held, Letter grade in class, Class Rank

Sample

- a subset of the population

Data Set

- all the data collected in a particular study are referred to as the data set for the study - a data set with n elements contains n observations

Sample Survey

- collecting data for a sample

Census

- collecting data for the entire population

Existing Sources

- data already collected by earlier researchers

Categorical Data

- data that consists of names, labels, or other nonnumerical values

Quantitative Data

- indicates how many or how much, always numeric - ordinary arithmetic operations are meaningful for quantitative data

Nominal Scale

- measurement in which numbers are assigned to objects or classes of objects solely for the purpose of identification - ex: Gender, College major, Blood type, Marital status, SSN, Zip Code, Student ID

Interval Scale

- measurement in which the assigned numbers legitimately allow the comparison of the size of the differences among and between members - ex: Celsius Temperature, Fahrenheit Temperature, IQ (intelligence scale), SAT scores, Time on a clock with hands

Ratio Scale

- measurement that has a natural, or absolute, zero and therefore allows the comparison of absolute magnitudes of the numbers - ex: Weight, Height, Income earned in a week, Number of children, Years of education

Observation

- the set of measurements obtained for a particular element

A study took random sample of adults and asked them about their bedtime habits. The data showed that people who drank a cup of tea before bedtime were more likely to go to sleep earlier than those who didn't drink tea.Which type of study method is this? A. Experimental study B. Observational study C. Existing sources

B. Observational study

The owner of a factory regularly requests a graphical summary of all employees' salaries. The graphical summary of salaries is an example of: A. a census B. descriptive statistics C. an experiment D. statistical inference

B. descriptive statistics

Parking at a university has become a problem. University administrators are interested in determining the average time it takes a student to find a parking spot. An administrator inconspicuously followed 120 students and recorded how long it took each of them to find a parking spot. Identify the sample of interest to the university administration. A. the entire set of students that park at the university B. the 120 students that data was collected from C. a single student that parks at the university D. the parking time, defined to be the amount of time the student spent finding a parking spot

B. the 120 students that data was collected from

A pediatrician randomly selected 10 parents of his patients. Then he surveyed the parents about their opinions of different kinds of diapers.Identify the population and sample in this setting. A. The population is the parents of the pediatrician's patients who wear diapers; the sample is the parents of all of the pediatrician's patients. B. The population is the pediatrician's patients; the sample is the 10 patients selected. C. The population is the parents of the pediatrician's patients; the sample is the 10 parents of patients selected.

C. The population is the parents of the pediatrician's patients; the sample is the 10 parents of patients selected. - The population is the entire group of people or things we want to study.The sample is the part of the population that we actually collect data from. The pediatrician only sampled from parents of his patients, not from the patients themselves. He also sampled from all of the parents, not only those whose children wear diapers.So the pediatrician surveyed 10 such parents. The population is the parents of the pediatrician's patients; the sample is the 10 parents of patients selected.

Social security numbers consist of numeric values. Social security number is a examples of: A. a quantitative variable which uses interval scale of measurement B. a quantitative variable which uses ratio scale of measurement C. a categorical variable which uses nominal scale of measurement D. a categorical variable which uses ordinal scale of measurement

C. a categorical variable which uses nominal scale of measurement

A study randomly assigned volunteers to one of two groups: One group was directed to use social media sites as they usually do. One group was blocked from social media sites. The researchers looked at which group tended to be happier. Which type of study method is this? a. Existing Sources b. Experimental Study c. Observational Study

b. Experimental Study Experimental study manipulate the subjects' environment, then measure the response variable.

A factory overseer selects 40 threaded rods at random from those produced that week at the factory, then she tests their tensile strength. Identify the population and sample in this setting. a. The population is all threaded rods ever produced at the factory; the sample is the threaded rods produced that week. b. The population is threaded rods produced at the factory that week; the sample is the 40 threaded rods selected. c. The population is all threaded rods in the world; the sample all threaded rods produced at the factory.

b. The population is threaded rods produced at the factory that week; the sample is the 40 threaded rods selected. The population is the entire group of people or things we want to study. The sample is the part of the population that we actually collect data from. The factory overseer did not sample from all threaded rods ever produced at the factory or from all threaded rods in the world. She was only interested in threaded rods produced at the factory that week. So the overseer selected 40 of those threaded rods.

A study took a random sample of people and examined their social media habits. Each person was classified as either a light, moderate, or heavy social media user. The researchers looked at which groups tended to be happier. Which type of study method is this? a. Existing Sources b. Experimental Study c. Observational Study

c. Observational Study Observational studies make no attempt to control the variables of interest