Basic SPSS for Postgraduate

Transcription

1 Basic SPSS for Postgraduate Dr. Shamshuritawati Sharif School of Quantitative Science shamshurita@uum.edu.my Office : Mobile :

2 In the process of carrying out the research, we need some clues about, How will we analyse our data? Which methods should we use? How do we decide if they are right or wrong methods?

3 The rationale to study statistics courses are to be able to: conduct research, read and evaluate journal articles, further develop critical thinking and analytic skills, and know when you need to hire outside statistical help

4 At the end of this workshop, you would be able to Identify the suitable method for analysing data Perform the analysis by using SPSS Report the statistical results correctly Main agenda of this workshop, we will help you with step by step instructions on how to use SPSS for statistical analysis AND how to write a statistical results in APA format

5 SPSS s Data entry Compulsory Make-up

6 Measurement Scale The process of describing some phenomenon of interest by assigning numbers or scores to attributes of people or objects in a reliable and valid way. Specifies what the researcher must do to measure the concept under investigation. To effectively carry out any measurement we need to use some form of a scale.

7 Measurement Scale A scale is any series of items (numbers) arranged along a continuous spectrum of values for the purpose of quantification (i.e. for the purpose of placing objects based on how much of an attribute they possess) The level of measurement is critical in determining the appropriate multivariate technique to use. Nominal, Ordinal, Interval, Ratio

8 1. Nominal Scale: The numbers are used only to group or sort responses. No order exists, a scale in which the numbers or letters assigned to an object serve only as labels for identification or classification, size of number is not related to the amount of the characteristic being measured, e.g. Gender (Male=1, Female=2), YES/NO scale, it has no order and there is no distance between YES and NO 2. Ordinal Scale: The numbers are ordered. a scale that arranges objects or alternatives according to their magnitude in an ordered relationship, larger numbers indicate more (or less) of the characteristic measured, but not how much more (or less) e.g. The simplest ordinal scale is a ranking. When a market researcher asks you to rank 5 types of juice from most flavorful to least flavorful, he/she is asking you to create an ordinal scale of preference.

9 3. Interval Scale: Differences between the numbers are ordered. A scale that both arranges objects according to their magnitude, distinguishes this ordered arrangement in units of equal intervals, but does not have a natural zero representing absence of the given attribute, contains ordinal properties, and in addition, there are equal differences between scale points, e.g. the temperature scale (40 o C is not twice as hot as 20 o C), 10-point rating scale : distance between 1 and 2 was the same as that between 7 and 8, TIME OF DAY on a 12-hour clock : difference between 1 and 2 pm is same as difference between 10 and 11 am When you are asked to rate your satisfaction with a piece of software on a 7 point scale, from Dissatisfied to Satisfied, you are using an interval scale. It is an interval scale because it is assumed to have equidistant points between each of the scale elements. This means that we can interpret differences in the distance along the scale. We contrast this to an ordinal scale where we can only talk about differences in order, not differences in the degree of order.

10 4. Ratio Scale: The number series has a unique origin indicated by the number zero. A scale that has absolute rather than relative quantities and an absolute (natural) zero where there is an absence of a given attribute, contains interval scale properties, e.g. income, age. A ratio scale is the top level of measurement and is not often available in social research.

11 Rating Scales 1. Itemized Rating Scale i. Simple category scale ii. Category scale iii. Likert scale (Summated ratings scale) iv. Semantic differential scale v. Stapel scale vi. Constant sum scale 2. Graphic Rating Scale

12 Simple Category Scale A category scale with only two response categories both of which are labeled. Example: Please rate car model A on each of the following dimensions: poor excellent a) Durability [ ] [ ] b) Fuel consumption [ ] [ ] Characteristics The scale has properties of a nominal scale.

13 Category Scale A rating scale which the response options provided for a closed-ended question are labeled with specific verbal descriptions. Example: Please rate car model A on each of the following dimensions: Poor Fair Good Very Good Excellent a)durability [ ] [ ] [ ] [ ] [ ] b)fuel consumption [ ] [ ] [ ] [ ] [ ] Characteristics: Response options are still verbal descriptions. Response categories are usually ordered according to a particular descriptive or evaluative dimension. Therefore scale has ordinal properties. However, researchers often assume that it possesses interval properties => but this is only an assumption.

14 The Likert Scale A multiple item rating scale in which the degree of an attribute possessed by an object is determined by asking respondents to agree or disagree with a series of positive and/or negative statements describing the object. Example: Attitude toward buying from the Internet Totally disagree Disagree Moderate Agree Totally agree a) Shopping takes dot dot [ ] [ ] [ ] [ ] [ ] b) It is a good thing that dot dot [ ] [ ] [ ] [ ] [ ] c) Buying products dot dot [ ] [ ] [ ] [ ] [ ] Characteristics The scale has properties of an ordinal scale.

15 Semantic Differential Scale A rating scale in which bipolar adjectives are placed at both ends (or poles) of the scale, and response options are expressed as semantic space. Example: Please rate car model A on each of the following dimensions: ============================================= Durable ---:-X-:---:---:---:---:--- Not durable Low fuel consumption ---:---:---:---:---:-X-:--- High fuel consumption ============================================= Poor Excellent Durability : Poor Excellent Fuel consumption : ============================================= Characteristics 1. The scale has properties of an interval scale. 2. Sometimes descriptive phrases are used instead of bipolar adjectives, especially when it is difficult to get adjectives that are exact opposites 3. It is often used to construct an image profile.

16 Stapel Scale A simplified version of the semantic differential scale in which a single adjective or descriptive phrase is used instead of bipolar adjectives. Example: Please rate car model A on each of the following dimensions: Model A Durable Car Good Fuel Consumption Characteristics 1. The scale measures both the direction and intensity of the attribute simultaneously. 2. It has properties similar to the semantic differential => interval scale.

17 Constant-Sum Scale A rating scale in which respondents divide a constant sum among different attributes of an object (usually to indicate the relative importance of each attribute). Example: Divide 100 points among the following dimensions to indicate their level of importance to you when you purchase a car: Durability Fuel Consumption Total 100 Characteristics The scale has properties of a ratio scale.

18 Graphic Ratings Scales This is also known as continuous rating scale Rating scales in which respondents rate an object on a graphic continuum, usually a straight line. The respondents rate the objects by placing a mark at the appropriate position on a line that runs from one extreme of the criterion variable to another. Example Characteristics The straight line scale has ratio scale.

19 Data classification Qualitative Data Categorical Data Non-metric Data Quantitative Data Continuous Data Metric Data Nominal Simple category scale Ordinal Category scale Likert scale Interval Semantic differential scale Stapel scale Ratio Constant sum scale Graphic Rating Scale

20 SPSS s Data entry Compulsory Make-up