A coding system is assigning values to the dummy variables. The values are assigned to the variables in numeric form such as 0, 1, 2, etc. For instance, sex is a categorical variable in which male and female is the dummy variable. For analysing the data, the variables should be in numeric form, thus, the values can be assigned to the dummy variables, that is, for male: “1” and for female: “2” can be assigned. Following is the coding system for the data given in Table 1:
For sex:
Male = 0
Female = 1
For profession:
Unemployed = U = 0
Professional = P= 1
Non-professional = N= 2
For yearly income:
< £15,000 = 0
£15,000 - £30,000 = 1
£31,000 £49,000 = 2
> £50,000 = 3
For owns or rents:
Owns = 0
Rents = 1
For diagnose with depression:
Yes = 0
No = 1
For HAM-D scores:
0-7 = normal
8-13 = mild depression
14-18 = moderate depression
19-22 = severe depression
=23 = very severe depression
Types of variables
There are two types of variables continuous variable and discrete variable. A continuous variable is a variable that can be subdivided. The number can be taken as a decimal number also (Healey, 2011, p.9). A discrete variable is a variable whose measurement unit cannot be subdivided. The integer is taken as a whole number such as 1, 2, or 3. The continuous variables are further categorized into interval variable and ratio variable. These two variables are the scale variables. The discrete variables are categorized into nominal variable and ordinal variable.
Nominal variable
The nominal variable is a categorical variable. The values can be assign to the nominal data but the data is not in order (Stephens, 2009, p.5).
Ordinal variable
The ordinal variable is a variable that must be in order. An ordinal data is a data that can be ranked and can have a rating scale. It can be put in order but cannot be measured (Velleman & Wilkinson, 1993, p.67).
Interval variable
The interval variable is a variable in which there is a difference between the two values and the difference is meaningful in interpreting the data.
Ratio variable
A ratio variable contains the properties of an interval variable. The ratio variable is a scalar variable and values can be assigned to the ratio data. It can be arranged in an order and the differences can be arithmetically measured and interpreted.
In the Table 1, following is the classification of the variables:
Variables
Type of variable
Gender
Nominal
Number of children
Ratio
Profession
Nominal
Yearly income
Ratio
Owns or rents
Nominal
Diagnosed with depression
Nominal
HAM-D scores
Ordinal
Types of statistical tests
The types of statistical tests that can be performed for the data mentioned in table 1 are descriptive analysis and relational analysis. The descriptive analysis shows the measurement of central tendency by analyzing the mean, median, mode, and variance of the data. It will further give the histograms that are graphical presentation. The normal distribution curve, skewed distribution curves, bimodal distribution curves, etc can be identified by using descriptive analysis. Moreover, the relational statistics can also be applied in this ...