2.3 - Statistics & Scales

Descriptive Statistics

deals with organizing and summarizing observations so that they are easier to comprehend

Descriptive Statistics

used to describe the basic features of the data in a study

Descriptive Statistics

provide simple summaries about the sample and the measures

Descriptive Statistics

aims to describe data by means of frequencies, ranks, percentages, measures of central tendency and variability

Inferential Statistics

are methods used to make inferences from observations of a small group of people known as sample to a larger group of individuals known as population

ALL are Descriptive

Identify if the given speaks of descriptive or inferential statistics:

1. There are 15 boys and 11 girls in the class of Mrs. Claro.

2. 58% of the chocolates sold in the Philippines are imported.

3. 29% of the respondents were females.

4. 14 out 20 were given a chance to participate in the study.

5. Fifty people were gathered to attend the event

Measurement

the application of rules for assigning numbers to objects

• The rules are the specific procedures used to transform qualities of attributes into numbers

Measurement

the process of assigning numbers to observations by making use of certain instrument (s)

• Magnitude

• Equal Intervals

Properties of Scales (2)

Magnitude

the property of “moreness”

Magnitude

If a scale has magnitude, you can compare items and say:

• More, less, or equal.

Magnitude

is the property of a scale that tells us “how much” of something exists.

Magnitude

On a stress scale of 1–10

• Alice scores 7, Bob scores 4.

• Because the scale has ______, we can say Alice has more stress than Bob.

Equal Intervals

happens if the difference between two points at any place on the scale has the same meaning

• as the difference between two other points that differ by the same number of scale unit

Equal Intervals

Allows addition and subtraction to compare differences.

Equal Intervals

On a temperature scale in Celsius:

• 20°C to 30°C is the same difference in heat as 70°C to 80°C.

• Nominal

• Ordinal

• Interval

• Ratio

Types of Scales (4)

Nominal scale

really not scale at all; its only purpose is to name objects

• consists of numbers which indicate categories for purely classification purposes

Nominal scale

Example: Sex: M = 1 F = 2

Nominal scale

it doesn’t have a property of magnitude, equal intervals and absolute zero

Ordinal scale

allows you to rank individuals or objects

• but not to say anything about the meaning of the differences between the ranks.

Ordinal scale

it is a scale with the property of magnitude but not equal intervals or an absolute zero

Ordinal scale

Example: Likert-type scale

• Strongly agree = 1

• Agree = 2

• Indifferent = 3

• Disagree = 4

• Strongly disagree = 5

Interval scale

Has all properties of an ordinal scale – you can rank or order items.

• Equal intervals

• Shows “how much better” one value is compared to another.

• No absolute zero

• (zero does not mean “nothing.”)

Interval scale

Example:

IQ – there is a meaningful difference between an IQ of 110 and 109 but the test does not measure people who have no intelligence

Ratio scale

the most advanced and precise measurement scale

• Possesses all the characteristics of the interval scale

• Absolute zero

• seldom used in assessment

Ratio scale

• Weight: 0 kg means no weight; 10 kg is twice as heavy as 5 kg.

• Height: 0 cm means no height; 180 cm is twice as tall as 90 cm.

• Nominal

• Ordinal

• Interval

• Interval

• Nominal

• Ratio

Identify if it is nominal, ordinal, interval, or ratio scale.

1. Eye color

2. Educational Level

3. School grades

4. Temperature (Celsius)

5. Brand of phones

6. Weight (kg)