Presentation 9-Measurement

Question 1

Measurement

Answer 1

This refers to the process of describing abstract concepts in terms of specific indicators by the assignment of numbers of other symbols to these indicants in accordance with rules.

Question 2

Ways of measuring

Answer 2

Use of indicators, which are observations that are assumed to be evidence of the attributes or properties of the variable itself. (Ratio, percentage).

Question 3

Item

Answer 3

is used to refer to a single indicator of a variable.

Question 4

Levels of measurement

Answer 4

are the rules that define permissible mathematical operations that can be performed on a set of numbers produced by a measure.

Question 5

How many levels of measurement?

Answer 5

Four

Question 6

Nominal levels

Answer 6

Classify observations into mutually exclusive categories. They represent nominal variables at the theoretical level eg. sex, ethnicity, religion.

Question 7

Levels of measurement

Answer 7

1.Ordinal Measures
2.With this we can speak of a given category as ranking higher or lower than some other category. It does not mean that the categories are equally spaced eg. socio economic group.
3.Like nominal scales, ordinal scales cannot be added, subtracted multiplied or divided. The only characteristics they (ordinal measures) have that nominal does not have is the fixed order of the categories.
4.Interval measures-These share the characteristics of ordinal scales – mutually exclusive categories and inherent order but also have equal spacing between the categories. As interval scale occurs if the difference between scores of eg. 70 and 80 are the same eg. 10.
5. Ratio Measurements-This is the highest level of all the measurement. Ratio have all the measurement. Ratio have all the characteristics of interval measures, but the zero point is absolute and meaningful rather than arbitrary. With ratio measures, statements can be made to the effect that some score is given ratio of another score.

Question 8

Errors in measurement

Answer 8

There are basic types of errors of measures.
Random Errors
These are neither consistent nor patterned eg. A respondent may misread or mismark an item on a questionnaire. They are essentially chance errors and can occur at any point of the research project.

SYSTEMATIC ERRORS
These are consistent and patterned. They cannot cancel themselves out. These are likely to lead to false conclusions. Eg. crime, delinquency.

Question 9

The process of measurement-Averages

Answer 9

Average is frequently referred to as a measure of central tendency.Many people do not realise there are more than one average. The choice of the average will depend on what is being measured.

Question 10

The process of measurement- Median

Answer 10

The median is the middle element in a set of data when it has been arranged in order, eg. putting people in order of weight or height, the median would be the middle term if the number of elements is odd. When the number of elements is even the median is found by averaging the middle two elements. The median of 1,3,5,7,8,9 is 6

Question 11

The process of measurement- Mode

Answer 11

The Mode
The mode is often referred to as the typical average. It is the name given to the element which occurs most frequently in a set of data.
Examples 50 students were given the choice of 9 books to read.
From the table of their choice you will see that books number 5 was the most popular.
Books offered 1 2 3 4 5 6 7 8 9
Number who choose 2 4 6 7 12 9 5 4 1
The most popular book was five which is called the mode.

Question 12

The process of measurement- Mean

Answer 12

This is the measure of central tendency most people think of when they hear the word average. It is calculated by summing all the values in a distribution and dividing by the number of cases. This is only suitable for interval or ratio level data, where there is equal spacing along a scale and various mathematical functions can be performed.

Question 13

The process of measurement- Representation of data

Answer 13

Representation of Data
For many diagrams may convey quickly far more information than a table, although tables may show more detailed information.
However, tables tend to be dull and people shy away from them. Methods of illustration are pie charts, bar charts.

Question 14

The process of measurement- Histogram

Answer 14

This is the most graphical display for showing the statistical distribution of a collection of numbers.
Such a graph is called a histogram because the rectangle are usually bar-shaped – that is much taller than wide. A histogram is also known as a bar graph. A histogram is similar to a bar chart except that it is a graphical representation of a frequency distribution. The frequency distribution of the bar is represented by its area rather than its height in the Histogram both axes show numbers. A Histogram is a refinement of a bar chart where adjoining bars touch, indicating continuous interval or ratio data. The width of each bar is the class interval and may be unequal. The height is the frequency of the class. Thus, frequency is represented by area.
The vertical axis shows frequency. The horizontal axis shows elements of groups of elements.
In the histogram the area of the columns represents the frequency

Question 15

Statistics-histogram

Answer 15

consists of tabular frequencies, shown as adjacent rectangles, erected over discrete intervals (bins), with an area equal to the frequency of the observations in the interval.
The height of a rectangle is also equal to the frequency density of the interval, i.e., the frequency divided by the width of the interval. The total area of the histogram is equal to the number of data.

Question 16

Statistics-bar chart

Answer 16

is graphical illustration of a frequency distribution in which the data is represented by a series of vertical or horizontal bars and a chart with rectangular bars with lengths proportional to the values that they represent. The bars can also be plotted horizontally.

Question 17

What are bar charts used for?

Answer 17

for plotting discrete (or ‘discontinuous’) data i.e. data which has discrete values and is not continuous. Some examples of discontinuous data include ‘shoe size’ or ‘eye colour’, for which you would use a bar chart. In contrast, some examples of continuous data would be ‘height’ or ‘weight’. A bar chart is very useful if you are trying to record certain information whether it is continuous or not continuous data.

Question 18

Statistics-pie chart (easy)

Answer 18

is a graphical presentation of proportional data which consists of a circular diagram divided into segments so that the area of each is proportional to the segment represented.)

Question 19

Statistics- pie chart (complicated)

Answer 19

is a circular chart divided into sectors, illustrating proportion. In a pie chart, the arc length of each sector (and consequently its central angle and area), is proportional to the quantity it represents. When angles are measured with 1 turn as unit then a number of percent is identified with the same number of centiturns. Together, the sectors create a full disk. It is named for its resemblance to a pie which has been sliced.

Question 20

What are pie charts used for?

Answer 20

can be an effective way of displaying information in some cases, in particular if the intent is to compare the size of a slice with the whole pie, rather than comparing the slices among them.[1] Pie charts work particularly well when the slices represent 25 to 50% of the data,[9] but in general, other plots such as the bar chart or the dot plot, or non-graphical methods such as tables, may be more adapted for representing certain information.It also shows the frequency within certain groups of information.