UNIT 3: Exploring Data with Tables and Graphs

Variable

a particular attribute of interest that is measurable or observable on each and every individual or object.

Data

- is any factual information or observation.

- It is a value of a variable.

Qualitative

Categorical variables

Qualitative

have labels or names rather than numbers, assigned to their categories.

Quantitative

are variables that are classified according to numerical value.

Discrete variables

can assume values that are obtained by counting

Continuous variables

may take any value within a defined range of values. The possible values of the variable belong to a continuous series

Nominal Scale

data obtained are names / labels, categories without any implicit or explicit ordering of the labels

Ordinal Scale

-data obtained are labels / classes with an implied ordering in these labels

-ranking can be done on the data

Interval Scale

data collected can be ordered, and in addition, may be added or subtracted, but not divided nor multiplied.

Ratio

data collected has all the properties of the interval scale, and in addition can be multiplied and divided

Textual Presentation of Data

method of presenting the collected data in organized and narrative (paragraph) form.

Tabular Presentation of Data

method of presenting the collected data by means of tables.

Heading

contains table number and table name

Box head

categories contained in the column

Stub

labels

Body

quantitative data

Foot notes

information about data

Frequency distribution

summary of the categories with their corresponding frequency

Frequency

-actual presentation

-actual count

Relative Frequency

use to compare different distribution of the same situation

Nominal data

-categorize are alphabetize

-chronological order

Ordinal Data

categories are in rank order

Simple Frequency

short gap between lowest and highest data.

Grouped Frequency

wide gap between the highest to lowest class intervals.

Graphical Presentation of Data

method of presenting data by means of graphs, charts or pictures.

Graphs

pictures of numerical data

Bar Graphs

useful for making direct visual comparisons over a period of time.

Compound (Multiple) bar graph

use to compare two or more variables

Component bar graph

divides or breaks down the quantities into their components.

Line Graphs

useful for plotting data over a period of time to indicate patterns or trends. The pattern is used to make predictions.

Pie / Circle Graphs

shows the relative sizes of parts of a whole.

Pictograph

-use icons/pictures to symbolize the quantities being presented.

- show changes in quantity- make comparison between similar situations.

Map Graph / Cartogram

best way to represent geographical data.

Dot plots

it is a simple way to display numerical data when the data set is reasonably small.

Frequency Distribution Table

statistical table showing the frequency or number of observation contained in each defined classes or categories.

Class Frequency

refers to the number of observations belonging to a class interval.

Class Interval

is a grouping or category defined by a lower limit and upper limit

Class Size / Class Width (c)

difference between two successive lower class limits.

Class Boundaries

are more precise expressions of the class limits by at least 0.5 of their values.

Class Marks / Midpoints

single values that represent every class intervals.

class boundaries

- exact limits/true limits

- used to make scale continuous

Cumulative frequency

tabular summary of a set of data showing the total number of data items less than or equal to the upper limits of each class.

Histogram

-bar graph

-consists of a set of rectangles having bases on a horizontal axis which centers on the class marks.