Chapter 2: Graphical Descriptive Techniques I

Question 1

Methods of descriptive statistics

Answer 1

Graphical
Tabular
Numerical

Question 2

Descriptive statistics

Answer 2

Arranging, summarizing and presenting a set of data in such a way that useful information is produced.

Question 3

Factors that determine appropriate statistical method

Answer 3

Most importantly:
Type of data
Information that is needed

Question 4

Objective of statistics

Answer 4

To extract information from data

Question 5

Variable

Answer 5

Some characteristic of a population or sample (that can change within the population)

Question 6

Values of a variable

Answer 6

Possible observations of the variable

Question 7

Data

Answer 7

The observed values of a variable (plural)

Singular = datum

Question 8

Types of data

Answer 8

Interval
Nominal
Ordinal

(Also ratio but for statistics ratio = interval)

Question 9

Interval data

Answer 9

Real numbers

Quantitative or numerical

Intervals between values are meaningful

All calculations are valid

Data may be treated as ordinal or nominal

Question 10

Nominal data

Answer 10

Categories

(Generally assigned numbers for analysis purposes, but numbers could be randomly assigned, order does not matter)

Qualitative or categorical

Only calculations based on frequency or percentage of occurances allowed

Cannot be treated as other kind of data

Question 11

Ordinal data

Answer 11

Appears nominal except the order or the values has meaning (scales). Order of values matter

Any code that preserves the order will produce the same result. Intervals are not meaningful!

Calculations based on ordering process are valid

Data may be treated as nominal (not interval)

Question 12

Calculations for interval data

Answer 12

All calculations permitted

Question 13

Nominal data

Answer 13

No calculations permitted - averages are meaningless. Percentages of occurances (frequency) is meaningful

Question 14

Ordinal data

Answer 14

Only permissible calculations involve ranking in order (median)

Question 15

Hierarchy of data

Answer 15

In order of permissible calculations
From interval (all computations allowed) to nominal (no calculations allowed but frequencies)

High level data may be converted to low level data (but only if necessary) but not vise versa

Question 16

Frequency distribution

Answer 16

Table presenting categories of nominal data and their frequencies

Question 17

Relative frequency distribution

Answer 17

Lists categories and the proportion with which each occurs

Question 18

Graphical presentation of nominal data

Answer 18

Bar chart and pie chart

Both good for simple presentation of numbers associated with categories IF it enhances understanding

Question 19

Bar chart

Answer 19

Generally used to display frequencies

Question 20

Pie chart

Answer 20

Generally used to show relative frequencies (as always showing parts of a whole)

Question 21

Graphical presentation of ordinal data

Answer 21

Same techniques as nominal (bar charts and pie charts)

Bar charts- bars in ascending or descending ordinal values

Pie charts- wedges typically arranged clockwise (ascending or descending)

Question 22

When to use frequency and relative frequency tables and bar and pie charts

Answer 22

1) objective is to describe a single set of data

2) data type is nominal or ordinal