Lecture 1 (DESCRIPTIVE STATISTICS)

Question 1

UNGROUPED DATA

Answer 1

Have not been summarised in any way

RAW DATA

Question 2

GROUPED DATA

Answer 2

Have been organised into a frequency distribution.

Question 3

FREQUENCY DISTRIBUTION

Answer 3

Summary of data presented in the form of class intervals and frequencies. 
Vary in shape and design.
Constructed according to the individual researcher's preferences.

Question 4

Steps in producing a frequency distribution.

Answer 4

1: Determine the range of frequency distribution.
2: Determine the number of classes - min 5, max 15
3: Determine the width of the class interval. Dividing range by the number of classes.
Round to a convenient number.

Question 5

Why should the number of classes be between 5 and 15?

Answer 5

Fewer than 5 classes causes excessive summarisation.

More than 15 leaves too much detail.

Question 6

Class midpoint.

Answer 6

The midpoint of each class interval. 
= beginning class endpoint + ending class end point /2

Question 7

RELATIVE FREQUENCY

Answer 7

The relative frequency is the proportion of the total frequency that is any given class interval in a frequency distribution. 
= individual class frequency / total frequency

Question 8

CUMULATIVE FREQUENCY

Answer 8

The cumulative frequency is a running total of frequencies through the classes of a frequency distribution.

Question 9

HISTOGRAM

Answer 9

Vertical bar chart of frequencies.  
It is a type of vertical bar chart where the area of each bar is equal o the frequency of the corresponding interval. 
Put data into class intervals.

Question 10

FREQUENCY POLYGON

Answer 10

Line graph of frequencies.
Constructed by plotting a dot for the frequencies at the class midpoints and connecting the dots.

Question 11

OGIVE

Answer 11

Line graph of cumulative frequencies.
Plotted by graphing a dot at each class endpoint for the cumulative frequency value and connecting the dots,

Question 12

PIE CHART

Answer 12

Proportional representation for categories of a whole.

Question 13

STEM AND LEAF PLOT

Answer 13

Graphical method displaying data by separating each number into two groups - a stem and a leaf

Question 14

PARETO CHART

Answer 14

Type of chart which contains both bars and a line graph.
Bars display the data in descending order, and the line graph shows the cumulative totals of each category, left to right. The purpose is to highlight the most important among a (typically large set of factors).

Question 15

SCATTER PLOT

Answer 15

Type of display using Cartesian coordinates to display value for two variables for a set of data. The data is displayed as a collection of points, each having the value of on variable determining the position on the horizontal axis and the value of the other variable determining the position on the vertical axis.

Question 16

How to construct a pie chart?

Answer 16

Proportion each value is of total value multiplied by 360.