stat 113 - objective 1 (based off slides)

What is a measurement obtained from a sample called?

Statistic

What is the collection of all objects under study called?

Population

What is a measurement obtained from every object of a population called?

Parameter

What is a smaller collection of objects from the population called?

Sample

What is the key difference between a parameter and a statistic?

A statistic is always knowable, while a parameter may be impractical or impossible to know.

How can variables in statistics be classified?

As quantitative or categorical (qualitative).

What defines a quantitative variable?

A variable whose values are numbers representing amounts or quantities.

What defines a categorical (qualitative) variable?

A variable whose values are categories, measuring 'kind' or 'type' rather than 'quantity' or 'amount'.

What is the nominal level of measurement?

The lowest level of measurement with categories that have no natural ranking or ordering.

What is an example of a nominal level variable?

Gender

What is the ordinal level of measurement?

A level where values have a natural ranking or ordering.

What is an example of an ordinal level variable?

Ratings such as 'superb', 'good', and 'unsatisfactory'.

What is the interval level of measurement?

A level where differences between values are meaningful, but there is no meaningful zero.

What is an example of an interval level variable?

Temperature in Celsius (0°C does not mean absence of temperature).

What is the ratio level of measurement?

The highest level of measurement with meaningful zero and properties of the interval level.

What is an example of a ratio level variable?

Weight at birth, where 0 pounds means absence of weight.

What is a discrete variable?

A quantitative variable with a finite or countable number of possible values.

What is a continuous variable?

A quantitative variable with an infinite number of possible values that are not countable.

What is an observational study?

A study where the researcher observes what is currently happening or what has happened in the past.

What is a designed experiment?

An experiment where the researcher manipulates conditions to determine the effect on the response variable.

What is a response variable?

The aspect being measured for each experimental unit.

What is an explanatory variable?

The variable manipulated by the researcher to examine changes in the response variable.

What is a double-blind experiment?

An experiment where neither the participants nor the person interacting with them knows which treatment is assigned.

What is a completely randomized experiment?

An experiment where participants are randomly assigned to groups and then groups are randomly assigned to treatments.

What is a confounder?

A variable whose effect on the outcome cannot be distinguished from the effect of different treatments.

What is the goal of an observational study?

To describe a group or situation, compare groups, or examine relationships between variables.

What are the two types of observational studies?

Prospective study and retrospective study.

What is a prospective study?

A study where participants are identified in advance, and data are collected over time.

What is a retrospective study?

A study where data are collected after the outcome has occurred using past records.

What is a confounder in an observational study?

A variable that influences both the dependent variable and independent variable, making it difficult to determine the effect of the independent variable.

In the exercise program study, what confounder was identified?

Alcohol consumption.

What is blocking in the context of reducing confounders?

Grouping participants who are similar in some way to control for variables that may affect the outcome.

What is a matched pairs approach?

A method where participants are paired based on similar characteristics to reduce confounding variables.

What is sampling bias?

A bias that occurs when the method of obtaining the sample favors one part of the population over another.

What can cause sampling bias?

Undercoverage, which occurs when a segment of the population is less represented in the sample.

What historical example illustrates sampling bias?

The Literary Digest poll in 1936, which incorrectly predicted the election outcome due to biased sampling methods.

What is voluntary response bias?

Bias that occurs when individuals choose to participate in a study, often leading to unrepresentative samples.

What are common scenarios that lead to voluntary response bias?

Polls on social media, radio call-ins, and advertisements asking for opinions.

What is response bias?

When survey responses do not reflect the true feelings of the respondents.

Give an example of response bias.

Participants overestimating their push-up abilities in a survey compared to actual performance.

What is nonresponse bias?

Bias that occurs when individuals selected for a sample do not respond, leading to differences in opinions between responders and nonresponders.

Why is nonresponse bias a concern in surveys?

It can skew results if the nonresponders have different opinions than those who do respond.

What are three common ways to organize qualitative data?

Frequency distribution, bar graph, and pie chart.

What is a frequency distribution?

A list that shows each category of data and the number of occurrences for each category.

What is relative frequency?

The proportion or percent of observations within a category, calculated as Frequency divided by the Sum of all frequencies.

What is a histogram?

A graphical representation of data using rectangles to show the frequency of data points within specified ranges.

How is a stem-and-leaf plot structured?

Digits to the left of the rightmost digit form the stem, while the rightmost digits form the leaves.

What is the purpose of a pie chart?

To represent qualitative data as a circle divided into sectors, where each sector's area is proportional to the frequency of the category.

What is the importance of checking the total frequency in a frequency distribution?

To ensure that the total frequency equals the number of observations in the data set.

What is the significance of interpreting relative frequency histograms?

They help to understand the distribution of data points across different categories relative to the total sample size.

What are the shapes of discrete distributions?

They can vary, but common shapes include uniform, binomial, and Poisson distributions.

What is the role of data organization in statistical analysis?

To simplify the interpretation of data and facilitate comparisons between different categories or groups.

What is the relationship between data organization and bias?

Proper organization of data can help identify potential biases and confounding variables in a study.

What is the effect of demographic factors on voluntary response bias?

Certain demographics may be more likely to participate based on factors like free time, wealth, or education level.

What is the impact of nonresponse bias on survey results?

It can lead to skewed results if the opinions of nonresponders differ significantly from those who respond.

Still learning (4)

You've started learning these terms. Keep it up!