cscc stat 2430

A ___ is the entire group of interest for a study.

Population

A ___ is a subset of individuals, selected from the population, that we collect data about and analyze.

Sample

___ Data - consists of names or labels (representing categories).

Qualitative

___ Data - consists of numbers representing counts or measurements.

Quantitative

What is a level of Measurement ?

Another way to classify data

What are the 4 different levels of measurement?

Nominal, Ordinal, Interval, Ratio

What are the 2 types of qualitative levels of measurements?

Nominal, Ordinal

What are the 2 types of quantitative levels of measurements?

Interval, Ratio

Ordinal is …

categorical data that does have a specific ordering scheme (such as low to high), (ex: letter grades, year of school)

Nominal is …

categorical data that does not have a particular order. (ex: brand, color, race)

Ratio is …

numerical data that has a natural zero starting point that indicates a quantity of none. (ex: money, height, weight, age)

Interval is …

numerical data that has no natural zero starting point. (arbitrary zero) (ex: temp, pants size, year)

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 (n = sample size = number of individuals in the sample)

Simple Random Sampling (SRS)

Randomly select some starting point and then select every ith element. (ex: starting at a random point looking a every 15th part made by a machine)

Systematic Sampling

Subdivide the population into at least two different subgroups that share the same characteristics, then draw a random sample from each subgroup (or strata).

Stratified Sampling

Divide the population area into sections (or clusters). Then randomly select some of those clusters. Now choose all members from selected clusters.

Cluster Sampling

Choosing subjects that are the easiest to sample or reach.

Convenience Sampling

Subjects choose or volunteer to be in the sample.

Voluntary Response Sampling

Frequency is …

Counting of how often an outcome occurs.

How do you calculate relative frequency?

(class freq. / sum of all freq.)

How do you calculate class width?

(maximum data value) - (minimum data value) /

number of classes (ALWAYS ROUND UP)

What kinds of graphs are categorical?

Bar graph, pie chart

What kinds of graphs are numerical?

Histogram, dotplot, stemplot, line graph, scatterplot, time-series graph

How do you find the range of a statistic?

Max - min

___ - Divide the data into quarters (four equal parts).

Quartiles

How do we find interquartile range?

Q3 - Q1

How to we solve for z-score?

(x-μ)/σ

The ___ is the average of all the data points.

mean

___ is the middle or center data point in a sorted data set

Median