Statistics Q1

Population

the entire group of individuals, items, objects, or events that a researcher wants to study and draw conclusions about

Sample

a smaller, manageable group taken from a larger total group (called a population) to study and draw conclusions

Parameter

a fixed numerical value that describes a specific characteristic of an entire population

Example: The mean # of activities (mean number of glasses of milk drank per day by the 5 students)

Statistic

Corresponding mean for the sample

Example: “Corresponding mean for number of kids in English class".

Variable

any characteristic, number, or quantity that can be measured or counted, and whose value changes (varies) from person to person, place to place, or thing to thing

Example: “Amount of milk glass drank per day”

Data

a collection of numbers, facts, and measurements gathered to answer questions, spot patterns, or understand a group

Example: 1, 0, 1, 3, 4

Mean

Equal share balance point

Median

Ordered middle

Mode

Most frequently shown value

Example: 3, 4, 5, 5, 6, 14

Mode: 5

Categorical Data

information that sorts items into distinct groups or categories using names, labels, or descriptions instead of numbers (typically non-numerical values)

Examples: Names, Eye color, Gender

Quantitative

Measure or count an amount (numerical values)

Examples: Ages, Height, Weight

Statistical Claim

A conclusion or a statement presented as being supported by data

Sampling frame

The list or accessible group from which the sample can be selected

Claim reach

The people, objects, place, or time period the conclusion says it describes.

Relative Frequency

the frequency divided by the total number of observations (f/n).

Cumulative Frequency

the running total of frequencies added up row by row in a data set

Discrete Quantitative Data

Separate numerical counts

Examples: Number of shoes owned, Number of classes taken each school year, IQ Scores

Continuous Data

Numerical measurements: Weight, Height, Size

Boundary Language

Words such as less than, fewer than, from, and between that determine which values are included.

Data Sampling

Selecting and studying part of a population to learn about the whole population

Representative Sample

A sample that reflect relevant characteristics of the population closely enough to support the intended conclusion.

Random Sampling

A chance process gives population members a known opportunity to be selected

Simple random sample

Every possible sample of the same six has an equal chance of selection

Systematic Sample

Chose a random starting point, then select every kth member of an ordered frame

Convience Sample

Select people who are readily available: this is non-random

Population inference

Using a sample statistic to draw a conclusion about a population

Selection Bias

A systematic process that favors or excludes groups based on certain prejudices.

Question: Who has a greater chance to volunteer or be reached?

Stratified Sample

research method where you divide a total population into smaller, non-overlapping groups based on shared traits, then randomly pick samples from each group

Undercoverage

Groups in the population are absent from the sampling frame

Question: Who never had a path into selection?

Non responsive bias

People selected for the sample do not provide data

How might respondents differ from selected non-respondents?

Response Bias

Wording or influence changes the answers recorded

Question: What could push a person toward one response?