Unit 1 Stats

All the key terms for the first unit of stats

What is a Ratio?

has a natural starting point and a zero that makes sense (Heights, Length, Distances, Volumes)

What is a Interval?

are meaningful, but there is no natural zero starting point and ratios are meaningless (body temp)

What is Ordinal Data?

data that can be arranged in Order but difrrences either cant be found or are meaningless (ranks of colleges)

What is Nominal Data?

Categories only. Data cannot be arranged in order (eye colors)

Explain the Ratio test

Ask yourself the question, does the use of the term twice make sense?

Explain True Zero?

For a ratio to make sense there must be a value of true zero where 0 means none of it is present

What is a parameter?

a sub group of population

What is a statistic?

A sub group of a sample

What is Quantitve (Numerical) Data?

Data that consists of numbers (numerical) represents counts or measurements

What is Categorical (Qualitive attribute) Data?

Data consists of name’s or labels (not numbers that are counts or measurements)

What is Discrete Data?

results when the data values are quantitative and

the number of values is finite, or “countable

What is Continuous (numerical) data

result from infinitely many possible quantitative

values, where the collection of values is not

countable

What are the 2 ways to correct for missing data?

Delete Cases and Impute Missing Values

What are the two main ways to collect data in stats?

observational studies and experiments

What is an Experiment?

apply some treatment and then proceed to observe its

effects on the individuals.

are called experimental units, and they are often called

subjects when they are people.)

What is an Observational Study

observe and measure specific characteristics without

attempting to modify the individuals being studied

What is Replication?

is the repetition of an experiment on more

than one individual.

– Good use requires sample sizes that are

large enough so that we can see effects of treatments.

What is a Simple Random Sample?

A sample of n subjects is selected in such a way that

every possible sample of the same size n has the

same chance of being chosen.

is often called a random sample, but strictly speaking, a random sample has the weaker requirement that all members of the population have the same chance of being selected.

What is Systematic Sampling?

Select some starting point and then select every kth

element in the population.

What is Convenience Sampling?

Using data that are very easy to get.

What is Stratified Sampling

Subdivide the population into at least two different

subgroups (or strata) so that the subjects within the

same subgroup share the same characteristics. Then

draw a sample from each subgroup (or stratum).

What is Cluster Sampling

Divide the population area into sections (or clusters),

then randomly select some of those clusters, and

choose all the members from those selected clusters.

What are the types of Observational Studies

Cross-sectional study, Retrospective (or case control) study, Prospective (or longitudinal or cohort) study

What is a Cross-sectional study?

Data are observed, measured, and collected at one

point in time, not over a period of time.

What is a Retrospective (or case control) Study?

Data are collected from a past time period by going

back in time (through examination of records,

interviews, and so on).

What is a Prospective (or longitudinal or cohort) study?

Data are collected in the future from groups sharing

common factors (called cohorts).