Prob & Stats - Chapter 1

True or false: Using a systematic sample guarantees, that members of each group within a population will be sampled.

False. Using a stratified sample guarantees that members of each group within a population will be sampled.

Average humidity outside each month is an example of what level of measurement?

Interval

Statistics

Is the science of conducting studies to collect, organize, summarize, analyze, and draw conclusions from data.

In a study of all 3682 seniors at a college, it is found at 65% on a computer. Is this a parameter or statistic?

It is a parameter, because the value is a numerical measurement describing a characteristic of a population.

Genres of music: country, pop, hip-hop, jazz, rock, alternative, etc. are examples of what level of measurement?

Nominal

Type of blood (A, B. AB, O) is an example of what level of measurement?

Nominal

How much do you read each week? Is this statement biased or non-biased?

Non-biased

Sampling error

Occurs when the sample has been selected with a random method, but there is a discrepancy between the sample result, and the true population result

Name the data that can be qualitative.

Ordinal and nominal

Name the data that can be quantitative.

Ordinal, ratio, and interval

Everyone in the United States for a study of the average age of people in the US is an example of statistic or parameter?

Parameter

The students in this classroom when evaluating grades for this class is an example of statistic or parameter?

Parameter

Cluster sample

Partition the population into clusters (groups), then select all members of the selected cluster. (Certain blocks in a city, faculty at a college math department)

The age of each resident in an apartment building is an example of what?

Population, because it is a collection of ages for all people in the apartment building.

Grades of over the next two years of all the nursing students is an example of what type of study?

Prospective

Car colors in the parking lot and different breeds of dogs are examples of qualitative or quantitative?

Qualitative

Runners times to finish a race. Is this qualitative or quantitative?

Quantitative

Speed of cars traveling down I-20 is an example of what level of measurement?

Ratio

Replication

Repeating an experiment on one or more of the individuals. The larger the sample size the better, but a trade-off in cost must be considered.

What is replication in an experiment? Why is it important?

Replication is repetition of an experiment under the same or similar conditions. Replication is important because it enhances the validity of the results.

All the students to drop a class last semester is an example of which type of study?

Retrospective

The ages of 15 members of a legislature is an example of what?

Sample, because it is a collection of ages for some members of the legislature

The number of children in 4 houses on a street of 15 is an example of what?

Sample, because the collection of the number of children for 4 houses is a subset of all houses on the street.

All the students at MTC for a study of Southeast college students is an example of parameter or statistic?

Statistic

Telephone interview of 1,502 adults that are 18 years old or older found that only 69% could identify the current Vice-President. Is this value a parameter or a statistic?

Statistic

Peanuts are planted on a 52 acre field. The field is divided into 1 acre sub plots. A sample is taken from each sub plot to estimate the harvest. What type of sampling is use?

Stratified sampling is used, since the field is divided into subplots, and a random sample is taken from each sub plot.

Stratified sample

Subdivide population into strata (groups) with the same characteristic, then randomly sample within those strata. (100 married men, 100 married women were asked)

Every 12th person entering a restaurant is asked to choose his or her favorite meal from a list of five different meals that includes a description of each. What type of sampling is used?

Systematic sampling is used, because every 12th person is selected.

Ordinal

That I can be arranged in order, but differences between the data either can't be found or are meaningless. Qualitative or quantitative data.

A survey of 1,021 U.S. adults found that 45.1% have a favorable view of Cuba. Identify the sample.

The 1,021 U.S. adults selected

A survey of 1,500 U.S. adults found that 59.3% have never had a vaccine reaction. Identify the sample.

The 1,500 U.S. adults selected

To gather information about starting salaries at companies listed in a stock index, a researcher contacts 44 of the 300 companies. What is the population?

The 300 companies in the index.

To gather information about starting salaries at companies listed in a stock index, a researcher contacts 44 of the 300 companies. Identify the sample.

The 44 companies contacted.

A survey of 183 law firms in a country found that the average hourly billing rate for partners was $588. Describe the sample data set.

The average hourly billing rate for partners of 183 law firms was $588.

descriptive statistics

The branch of statistics that involves organization, summarization and display of data.

inferential statistics

The branch of statistics that involves using a sample to draw conclusions about a population. A basic tool used is probability.

Experimental units

The individuals being influenced, or if they are human, we refer to them as subjects.

A survey of 183 law firms in a country found that the average hourly billing rate for partners was $588. Identify the sample.

The law firms that were surveyed.

A survey of 2210 adults in a country found that 85% think that militant terrorists are a major threat to the well-being of their country. Is this a statistic or a parameter?

The number is a sample because it describes the people in a sample, which is a subset of all of the people in the country.

A survey of 1,021 U.S. adults found that 45.1% have a favorable view of Cuba. What is the population in the given problem?

The responses of all U.S. adults

A survey of 1,500 U.S. adults found that 59.3% have never had a vaccine reaction. What is the population?

The responses of all U.S. adults.

nonsampling error

The result of human error, including search factors as wrong data, entry, computing errors, questions with biased wording, faults data, provided by respondents, forming biased, conclusions, or applying statistical methods that are not appropriate for the circumstances.

nonrandom sampling error

The result of using a sampling method that is not random, such as using a convenience, sample or a voluntary response sample.

To gather information about starting salaries at companies listed in a stock index, a researcher contacts 44 of the 300 companies. Describe the sample set.

The starting salaries of the 44 companies.

A research study compared the memory retention of subjects when a learning activity was followed by a brief period of wakeful rest and when a learning activity was followed by a brief period of distraction. What type of study is this?

The study is experimental because it applies a treatment to the subjects.

In a survey of US employees, 42.3% of black women say they are uncomfortable sharing thoughts about racial inequality. What type of study is this?

The study is observational, because it does not apply a treatment to the employees.

Is the following qualitative or quantitative. Parcel tracking numbers

The variable is qualitative because tracking numbers are attributes or labels.

Is the following qualitative or quantitative. Postal zip codes.

The variable is qualitative because zip codes are attributes or labels.

Is the following qualitative or quantitative. Favorite types of foods

The variable is qualitative, because types are attributes or labels.

Is the following qualitative or quantitative. An amount of money.

The variable is quantitative because amount of money is found by measuring or counting

Every 12th person entering a restaurant is asked to choose his or her favorite meal from a list of five different meals that includes a description of each. What potential sources of bias are present?

The wording of the question may direct respondents towards a particular meal. If there is a regular pattern to the people entering the restaurant, the sample may not be representative.

ratio

There is a natural zero starting point, and rations makes sense

Convenience sample

Use data that are very easy to obtain

Blinding

Used when a subject does not know whether he or she is receiving a treatment or placebo.

Randomization

Used when individuals are assigned to different groups through a random process of selection.

Double blind

Used when the subject, and the person administering the experiment are unaware who is receiving the treatment or the placebo.

Data

Values measured, or observed that the variables can assume

Experiments

We apply some influence and record our data to see the results of its effects.

bias

Wording that might miss lead a person or calls a certain answer to be more prevalent.

Retrospective study (Case Study)

data are collected from a past time. But I'm going back in town through examination of records, interviews, and so on. (Students who dropped a class last semester, sales last quarter)

What are the two main branches of statistics?

descriptive and inferential statistics

Everyone in South Carolina for a study of all the United States is an example of statistic or parameter?

statistic

A survey of 1,021 U.S. adults found that 45.1% have a favorable view of Cuba. Describe the sample data set.

45.1% of the 1,021 U.S. adults who have a favorable view of Cuba and 54.9% of the 1,021 U.S. adults who do not.

A survey of 1,500 U.S. adults found that 59.3% have never had a vaccine reaction. Describe the sample set.

59.3% of the 1,500 U.S. adults who have never had a vaccine reaction and 40.7% of the 1,500 U.S. adults who have had a vaccine reaction.

Census

A count or measure obtained from an entire population

Sample

A group of subjects selected from a population.

statistic

A numerical measure, describing some characteristic of a sample

Parameter

A numerical measurement describing some characteristic of a population

What is the difference between parameter and statistic?

A parameter is a numerical description of a population. A statistic is a numerical description of a sample characteristic.

How is a sample related to a population?

A sample is a subset of a population.

Sampling

Account or measure obtained from part of a population.

A survey of 183 law firms in a country found that the average hourly billing rate for partners was $588. Identify the population.

All law firms in the country.

Why is a sample used more than a population?

Because it is nearly impossible to count the entire population.

How does social media influence the opinion in elections? Is this statement biased or non-biased?

Biased

Why does eating more fiber improve your health? Is this statement biased or non-biased?

Biased

interval

Can be ordered, differences are meaningful, but there is no natural zero starting point and ratios are meaningless

nominal

Categories only. That I cannot be arranged in order.

Observational study

Certain characteristics are measured and observe, but the experimenter does not attempt to modify the individual being studied.

What potential source of bias are present?

Certain grids may have been much more severely damaged than others. Severely damaged grids may have a few were occupied households. Certain grids may have been much more severely damaged than others. The grids that are selected may not be representative in terms of damage.

Peanuts are planted on a 52 acre field. The field is divided into 1 acre sub plots. A sample is taken from each sub plot to estimate the harvest. What potential sources of bias are present?

Certain subplots may have more or fewer peanut plants than others. Samples from these subplots may bias the overall sample.

After a wildfire, a disaster area is divided into 150 equal grids. 40 of the grids are selected, and every occupied household in the grid is interviewed to help focus relief efforts on what residents require the most. What type of sampling is used?

Cluster sampling is used, since the disaster area is divided into grids, and some of those grids are selected, and everyone in those grids is interviewed.

qualitative data

Consist of attributes, labels, or non-numerical entries

Quantitative data

Consist of numbers that are measurements or counts.

Populatuon

Consists of all subjects that are being studied.

Phone calls received during the last 10 minutes is an example of which type of study?

Cross-sectional

Pound of production this hour is an example of which type of study?

Cross-sectional

Prospective study (longitudinal or cohort)

Data are collected in the future from groups that share common factors.

Cross-sectional study

Data are observed, measured, and collected at one point in time, not over a period of time.

Systematic sample

Every kth subject is selected

True or false: A placebo is an actual treatment.

False. A placebo is a fake treatment

True or false. A statistic is a measure that describes a population characteristic?

False. A statistic is a measure that describes a sample characteristic.

True or false: A double blind experiment is used to increase the placebo effect.

False. Double blind is used to decrease the placebo effect.

True or false: The method for selecting a stratified sample is to order a population in some way, and then select members of the population at regular intervals.

False. The method for selecting a systematic sample is to order a population in some way, and then select members of the population at regular intervals.