Chapter 1 - Describing data: graphical

Question 1

Population

Answer 1

A complete list of all items of interest in research

Question 2

Sample

Answer 2

A specific part of the population

Question 3

Simple random sampling

Answer 3

A manner of selecting a sample of objects out of a population

A way which each member of the population is chosen completely by chance

The selection of one member does not have an influence on the probability of another member in the population being chosen

Question 4

Systematic sampling

Answer 4

Involves the selection of samples out of a list of the population

Question 5

Parameter

Answer 5

A numerical measure that describes a specific characteristic of a population

Question 6

Statistic

Answer 6

A numerical value that describes a specific characteristic of a sample

Question 7

Sampling error

Answer 7

Often results from the fact that only information about a part of the entire population is available

Question 8

Nonsampling errors

Answer 8

A type of error that can always occur

Unrelated to the kind of sampling procedure used

Question 9

Examples of non sampling errors include

Answer 9

The population sampled is not the relevant one

Survey subjects may give inaccurate or dishonest answers

There may be no response to survey questions

Question 10

Descriptive statistics

Answer 10

Focuses on graphical and numerical procedures that are used to summarise and process data

Describes the overall data

Question 11

Inferential statistics

Answer 11

Focuses on using the data to make predictions, forecasts, and estimates to make better decisions

Question 12

Categorical variables

Answer 12

Produce responses that belong to groups and categories

Question 13

Numerical variables

Answer 13

Can be split up into discrete and continuous variables

Question 14

Discrete variables

Answer 14

Countable values

Question 15

Continuous variables

Answer 15

Can take on any value within a given range of real numbers and usually arises from a measurement

Question 16

Qualitative data

Answer 16

There is no measurable meaning to the ‘difference’ in numbers

Question 17

Quantitative data

Answer 17

There is a measurable meaning to the difference in numbers

Question 18

Nominal scale

Answer 18

A scale used for labelling variables into distinct groups

Question 19

Ordinal scale

Answer 19

A variable measurement scale used to depict the order of variables but not the difference between each of the variables

Question 20

Interval scale

Answer 20

A numerical scale where the order of the variables as well as the difference between these variables is known

Question 21

Ratio scale

Answer 21

Almost the same as the interval scale

However it does have zero point

Question 22

Frequency distribution

Answer 22

A table used to organise data

Left column includes all possible responses on a variable being studied

The right column is a list of the frequencies, or number of observation, for each class

Question 23

Relative frequency distribution

Answer 23

Obtained by dividing each frequency by the number of observation and multiplying the resulting value by 100%

Question 24

Cross table

Answer 24

Lists the number of observations for every combination of values for two categorical or ordinal variables

Question 25

Pie chart

Answer 25

Used to draw attention to the proportion of frequencies in each category

Question 26

Pareto diagram

Answer 26

A bar chart that displays the frequency of defect causes

The bar on the left indicates the most frequent cause

The bar on the right indicate causes with decreasing frequencies

Question 27

Why is the Pareto diagram used?

Answer 27

Separate the vital few with the trivial many

Question 28

What are the 3 rules when constructing a frequency distribution

Answer 28

Determine k, the number of classes. This is decided in an arbitrary manner

Classes should be the same width, w. The width, w

Classes must be inclusive and non overlapping

Question 29

How to calculate the class width

Answer 29

(Largest observation - small observation)/number of classes

Question 30

Cumulative frequency distribution

Answer 30

Contains the total number of observation whose values are less than the upper limit for each class

We construct a cumulative frequency distribution by adding the frequencies of all frequency distribution classes up to and including the present class

Question 31

Relative cumulative frequency distribution

Answer 31

Cumulative frequencies can be expressed as cumulative proportion or percentages

Question 32

Histogram

Answer 32

A graph that consists of vertical bars constructed on a horizontal line that is marked off with intervals for the variable being displayed

Question 33

Ogive

Answer 33

A line that connects points that re the cumulative percent of observations below the upper limit of each interval in a cumulative frequency distribution

Question 34

Stem and leaf display

Answer 34

Alternative to the histogram

Data are grouped according to their leading digits and the final digits are listed separately for each member of a class

Question 35

Scatter plot

Answer 35

Can be prepared by locating one point for each pair of two variables that represent an observation in the data set

Question 36

What does a scatter show?

Answer 36

The range of each variable

The pattern of values over the range

A suggestion as to a possible relationship between the two variables

An indication of outliers