Statistics Vocab 1

What is a unit?

A unit is an object about which data is being collected

What is a variable?

A variable is a characteristics or property of an individual experimental unit in the population

A company tracked all credit card purchases during the year 2005 and measured two variables: (I) the cardholder's town of residence, and (2) the amount (in dollars)of each purchase. Is the variable (I) qualitative or quantitative?

Qualitative

A company tracked some credit card purchases during the year 2005 and measured two variables: (I) the type of credit card used (VISA, MasterCard, or American Express), and (2) the amount (in dollars)of each monthly balance. Is the variable (1) qualitative or quantitative?

Qualitative

A research company performed a study of Machiavellian traits in accountants. Machiavellian describes negative character traits that include manipulation, cunning, duplicity, deception, and bad faith. A questionnaire was administered to a random sample of 800 acccounting alumni of a large university; however, due to nonresponse and incomplete answers, only 264 questionnaires could be analyzed. Several variables were measured, including age, gender, level of education, income, job sati sfaction score, and Machiavellian ("Mach") rating score. The research findings suggest that Machiavellian behavior is not required to achieve success in the accounting profession. Identify the data-collection method used.

The data are from a survey.

A research company performed a study of Machiavellian traits in accountants. Machiavellian describes negative character traits that include manipulation, cunning, duplicity, deception, and bad faith. A questionnaire was administered to a random sample of 800 acccounting alumni of a large university; however, due to nonresponse and incomplete answers, only 264 questionnaires could be analyzed. Several variables were measured, including age, gender, level of education, income, job sati sfaction score, and Machiavellian ("Mach") rating score. The research findings suggest that Machiavellian behavior is not required to achieve success in the accounting profession. What type of data (quantitative or qualitative) is produced by each of the variables measured?

The quantitative variables are age, income, job satisfaction score, and Machiavellian rating. The qualitative variables are gender and level of education.

A research company performed a study of Machiavellian traits in accountants. Machiavellian describes negative character traits that include manipulation, cunning, duplicity, deception, and bad faith. A questionnaire was administered to a random sample of 800 acccounting alumni of a large university; however, due to nonresponse and incomplete answers, only 264 questionnaires could be analyzed. Several variables were measured, including age, gender, level of education, income, job sati sfaction score, and Machiavellian ("Mach") rating score. The research findings suggest that Machiavellian behavior is not required to achieve success in the accounting profession. Identify the sample.

The sample is the 264 accounting alumni who returned the questionnaire.

A company surveyed a random sample of 8,000 employees in the region. One question they asked was, "If your employer provides you with mentoring opportunities are you likely to remain in your job for the next five years?" They found that 640 members of the sample said yes. Is the variable quantitative or qualitative?

The variable is a qualitative variable. Its values cannot be expressed on a naturally occurring numerical scale.

Descriptive Statistics

Utilizes numerical and graphical methods to look for patterns in a data set, to summarize the information revealed in a data set, and to present that information in a convenient form

Inferential Statistics

Utilizes sample data to make estimates, decisions, predictions, or other generalizations about a larger set of data

3 different ways to collecting data

1. From a published source 2. From a designed experiment 3. From an observational study

Designed experiment

A collection method where the researcher exerts full control over the characteristics of the experimental units sampled. These experiments typically involve a group of experimental units that are assigned the treatment and an untreated group.

Observational study

A data collection method where the experimental units sampled are observed in their natural setting. No attempt is made to control the characteristics of the experimental units samples.

Explain how populations and variables differ.

A population is a set of units of interest to a study. A variable is a characteristic or property of the units being studied.

What is population?

A population is a set of units that are being studied

What is a sample?

A sample is a subset of the units of a population

What is a statistical inference?

A statistical inference is an estimate, prediction, or some other generalization about a population based on information contained in the sample

A research company performed a study of Machiavellian traits in accountants. Machiavellian describes negative character traits that include manipulation, cunning, duplicity, deception, and bad faith. A questionnaire was administered to a random sample of 800 acccounting alumni of a large university; however, due to nonresponse and incomplete answers, only 264 questionnaires could be analyzed. Several variables were measured, including age, gender, level of education, income, job sati sfaction score, and Machiavellian ("Mach") rating score. The research findings suggest that Machiavellian behavior is not required to achieve success in the accounting profession. What is the population of interest to the researcher?

All accounting alumni of the large university

A company surveyed a random sample of 8,000 employees in the region. One question they asked was, "If your employer provides you with mentoring opportunities are you likely to remain in your job for the next five years?" They found that 640 members of the sample said yes. Identify the population of interest to the company.

All employees in the region

Each month interviewers visit about 65,000 of the 90 million households in the region and question the occupants over 14 years of age about their employment status. Their responses enable the interviewers to estimate the percentage of people in the labor force who are unemployed. Define the population of interest to the interviewers.

All people in the region who are over 14 years old

Qualitative Data

Are measurements that cannot be measured on a natural, numerical scale; they can only be classified into one of a group of categories

Identify each of the following variables as qualitative or quantitative. Calories in a cheese danish a. Is the variable qualitative or quantitative? Why?

Calories in a cheese danish is a quantitative variable. Its values are numerical.

A company tracked all credit card purchases during the year 2005 and measured two variables: (I) the cardholder's town of residence, and (2) the amount (in dollars)of each purchase.

Population

Quantitative Data

Data that are measured on a naturally occurring numerical scale

Explain the difference between descriptive and inferential statistics.

Descriptive statistics describes sets of data. Inferential statistics draws conclusions about the sets of data based on sampling.

Identify each of the following variables as qualitative or quantitative. Dream vacation location Is the variable qualitative or quantitative? Why?

Dream vacation location is a qualitative variable. Its values are not numerical.

Each month interviewers visit about 65,000 of the 90 million households in the region and question the occupants over 14 years of age about their employment status. Their responses enable the interviewers to estimate the percentage of people in the labor force who are unemployed. What variable is being measured?

Employment status

Identify each of the following variables as qualitative or quantitative. Favorite baby name Is the variable qualitative or quantitative? Why?

Favorite baby name is a qualitative variable. Its values are not numerical.

A company surveyed a random sample of 8,000 employees in the region. One question they asked was, "If your employer provides you with mentoring opportunities are you likely to remain in your job for the next five years?" They found that 640 members of the sample said yes. Based on the question posed by the company what is the variable of interest?

If they answered yes to the survey question

Each month interviewers visit about 65,000 of the 90 million households in the region and question the occupants over 14 years of age about their employment status. Their responses enable the interviewers to estimate the percentage of people in the labor force who are unemployed. Is the problem of interest to the interviewers descriptive or inferential?

Inferential

A research company performed a study of Machiavellian traits in accountants. Machiavellian describes negative character traits that include manipulation, cunning, duplicity, deception, and bad faith. A questionnaire was administered to a random sample of 800 acccounting alumni of a large university; however, due to nonresponse and incomplete answers, only 264 questionnaires could be analyzed. Several variables were measured, including age, gender, level of education, income, job sati sfaction score, and Machiavellian ("Mach") rating score. The research findings suggest that Machiavellian behavior is not required to achieve success in the accounting profession. What inference was made by the researcher?

Machiavellian behavior is not required to achieve success in the accounting profession.

A research company performed a study of Machiavellian traits in accountants. Machiavellian describes negative character traits that include manipulation, cunning, duplicity, deception, and bad faith. A questionnaire was administered to a random sample of 800 acccounting alumni of a large university; however, due to nonresponse and incomplete answers, only 264 questionnaires could be analyzed. Several variables were measured, including age, gender, level of education, income, job sati sfaction score, and Machiavellian ("Mach") rating score. The research findings suggest that Machiavellian behavior is not required to achieve success in the accounting profession. How might the non responses impact the inference?

Nonrespondents may be more Machiavellian in nature, biasing the results.

Each month interviewers visit about 65,000 of the 90 million households in the region and question the occupants over 14 years of age about their employment status. Their responses enable the interviewers to estimate the percentage of people in the labor force who are unemployed. Is it quantitative or qualitative?

Qualitative

Identify each of the following variables as qualitative or quantitative. Is beverage preference qualitative or quantitative?

Qualitative

Identify each of the following variables as qualitative or quantitative. Is political party preference qualitative or quantitative?

Qualitative

Suppose you're given a data set that classifies each sample unit into one of four categories: A, B, C,or D. You plan to create a computer database consisting of these data, and you decide to code the data as A= 1, B = 2, C = 3, and D = 4. Are the data consisting of the classifications A, B, C, and D qualitiative or quantitative? After the data are input as 1, 2, 3, or 4, are they qualitative or quantitative? Are the data consisting of the classifications A, B, C, and D qualitiative or quantitative?

Qualitative, because they can only be classified into categories.

Suppose you're given a data set that classifies each sample unit into one of four categories: A, B, C,or D. You plan to create a computer database consisting of these data, and you decide to code the data as A= 1, B = 2, C = 3, and D = 4. Are the data consisting of the classifications A, B, C, and D qualitiative or quantitative? After the data are input as 1, 2, 3, or 4, are they qualitative or quantitative? After the data are input as 1, 2, 3, or 4, are they qualitative or quantitative?

Qualitative, because they cannot be meaningfully added, subtracted, multiplied, or divided.

A company tracked all credit card purchases during the year 2005 and measured two variables: (I) the cardholder's town of residence, and (2) the amount (in dollars)of each purchase.

Quantitative

A company tracked some credit card purchases during the year 2005 and measured two variables: (I) the type of credit card used (VISA, MasterCard, or American Express), and (2) the amount (in dollars)of each monthly balance. Is the variable (2) qualitative or quantitative?

Quantitative

Identify each of the following variables as qualitative or quantitative. Is distance of commute to work qualitative or quantitative?

Quantitative

Identify each of the following variables as qualitative or quantitative. Is number of children in a family qualitative or quantitative?

Quantitative

Explain the difference between qualitative and quantitative data.

Quantitative data are numerical in nature, while qualitative data are categorical in nature.

Measurement Error

Refers to inaccuracies in the values of the data recorded. In survey, this kind of error may be due to ambiguous or leading questions and the inter-viewers effect on the respondent.

Selection Bias

Results when a subset of the experimental units in the population is excluded so that these units have no chance of being selected in the sample.

Non Response Bias

Results when the researchers conducting a survey or study are unable to obtain on all experimental units selected for the sample.

A company tracked some credit card purchases during the year 2005 and measured two variables: (I) the type of credit card used (VISA, MasterCard, or American Express), and (2) the amount (in dollars)of each monthly balance. Does the data set collected represent a population or a sample?

Sample

Statistics

Sciences that deals with the collection, classification, analysis, and interpretation of information or data

Identify each of the following variables as qualitative or quantitative. Storage space on a computer drive Is the variable qualitative or quantitative? Why?

Storage space on a computer drive is a quantitative variable. Its values are numerical.

A company surveyed a random sample of 8,000 employees in the region. One question they asked was, "If your employer provides you with mentoring opportunities are you likely to remain in your job for the next five years?" They found that 640 members of the sample said yes. Describe the sample.

The 8,000 employees surveyed