Q SCI 381 Exam 1 (weeks 1-3)

What is statistics?

The science of collecting, organizing, analyzing, and interpreting data, often in order to make decisions

What is a statistic?

A value representative of an aspect of a sample/a numerical description of a sample

What are the branches of statistics?

Descriptive and Inferential

What is descriptive statistics?

Involves organizing, summarizing, and displaying data

What is inferential statistics?

Involves using sample data to draw conclusions about a population

What is data?

Information coming from observations, counts, measurements, or responses

What are the two levels of data collection?

Population and sample

What is a population?

the collection of all outcomes, responses, measurements, or counts that are of interest

How is a population defined?

By a scale

What is a sample?

A subset or part of the population that can refer to the individuals or objects of a population included in the dataset, or can refer to the dataset itself.

What is a parameter?

A numerical description of a population characteristic

In the field of inferential statistics, what do you use a sample statistic for?

To make inferences about population parameters, encapsulating uncertainty introduced via the sampling process

In order to make an unbiased inference about a population, the sample must...

Contain and cover the characteristics of the population

If the sample is biased towards a segment of the population then...

Any sample statistic will potentially be biased

What is a variable?

A characteristic of interest for each person or thing in a population

How are variables notated?

By capital letters, such as X or Y

What are some examples of variables?

Tree height, leaf color

What are the actual values of the variable?

Data

What are the two types of data?

Qualitative and quantitative

What is Qualitative data?

Consists of attributes, labels, or nonnumerical entities

What are some examples of qualitative data?

Major, place of birth, eye color

What is quantitative data?

consists of numerical measurements or counts, which can be continuous or discrete

What are the two types of quantitative data?

continuous and discrete

What are continuous values?

Those that can take any real number, whether it be a fraction, decimal, or negative value.

What are some examples of continuous values?

Temperature, weight, height

What are discrete values?

Those that can only take particular numeric values

What are some examples of discrete values?

Shoe size, counts

What are the four levels of measurement?

Nominal, ordinal, interval, and ratio

What is the nominal level of measurement?

Consists of names, labels, or qualities, and therefore is only qualitative data. There is no way to order this data, and no direct computations can be made with it.

What is an example of nominal level of measurement?

Eye color

What is the ordinal level of measurement?

Can be arranged in a specific order or ranked. Can be qualitative or quantitative. Gaps between units mean nothing.

What is an example of ordinal level of measurement?

Ranking ice cream flavors

What is the interval level of measurement?

Quantitative data only, data can be ordered. Differenced in gaps are meaningful. Zero represents a position on a scale, but isn't an inherent or absolute zero

What is an example of interval level of measurement?

Temperature

What is the ratio level of measurement?

Quantitative data only. Data can be ordered and gaps are meaningful. Zero represents and inherent or absolute zero.

What is an example of ratio level of measurement?

Distance

What levels of measurement can be put in categories?

Nominal, ordinal, interval and ratio

What levels of measurement can be arranged in order?

Ordinal, interval, and ratio

What levels of measurement have meaningful gaps?

Interval and ratio

What levels of measurement can you determine if one data value is a multiple of another?

Ratio

What is the first step when designing a study?

Identifying the variables of interest (the focus) and the population of the study. Might be framed as a research question.

What is the second step when designing a study?

Develop a detailed data collection plan. If this involves taking a sample, make sure the sample is representative of the population and avoids bias.

What is the third step when designing a study?

Collect data

What is the fourth step when designing a study?

Describe the data using descriptive statistics

What is the fifth step when designing a study?

Interpret the data and make decisions about the population using inferential statistics.

What is the sixth step when designing a study?

Identify any possible errors or sources of bias

What are the two types of statistical studies?

Observational and Experimental

What is an observational study?

When a researcher observes and measures characteristics of interest of part of a population, but does not change the conditions

What is an experimental study?

When a study has a treatment that is applied to part of a population and responses are observed relative to a control portion of the population, but all other factors within reason are controlled for

What can observational studies be used for?

To make unequivocal causal connections

What can experimental studies be used for?

To make causal connections between treatment and response

What are the tree categories of data collection?

Direct, survey, and simulation

What is direct data collection?

Involves the collection of data directly from designed studies

What is survey data collection?

An investigation of one or more characteristics of a population

What is simulation data collection?

A model is used to reproduce conditions of a situation or process

What are the four types of sampling?

Simple random, stratified, cluster, and systematic

What is simple random sampling?

Sample units are drawn at random from the entire sampled population with equal probability

What is stratified random sampling?

The population is divided into strata which are then sampled randomly

What is cluster sampling?

The population naturally falls into subgroups or sub-populations, each having similar characteristics.

What is systematic sampling?

Units are sampled in a regular scheme based on a random start point