Self-coded version of the NS-SEC

1. Introduction - When to use the self-coded NS-SEC

This section gives information and instructions on how to administer the five-class self-completion version of NS-SEC. NS-SEC is derived from occupation and employment status information, occupation being ideally coded to the most detailed level of the Standard Occupational Classification 2000 (SOC2000). As there are 353 unit groups within SOC2000, occupational coding is time-consuming and costly. Therefore there is a demand for a simpler and less expensive self-completion version of NS-SEC.

The five-class version of self-coded NS-SEC has the following classes:

2. Reliability of the self-coded NS-SEC

In comparisons of the self-coded and interviewer-coded five-class NS-SEC there was agreement in classifying 75 per cent of cases. It is apparent that the self-coded five-class NS-SEC is not as accurate as its interviewer-coded counterpart. Some disagreement between the two classifications may arise from coder error. Despite this, validation exercises show that the self-coded and interviewer-coded five-class NS-SECs display similar patterns and strength in their relationships with other variables, like smoking.

3. Questions to include in self-completion questionnaires

The self-coded version of NS-SEC is derived from a combination of information on:

• occupation (self-classified into eight categories), and

• an employment status variable that captures information on employment status and size of organisation.

The latter element of NS-SEC requires knowledge of whether an individual is:

• an employer, self-employed or an employee,

• size of organisation, and

• supervisory status

The following set of questions should be included in self-completion questionnaires in order to derive NS-SEC.

4. Derivation of five-class NS-SEC from self-coded occupational and employment status variables

There are three steps in deriving the five-class self-coded NS-SEC from the answers to questions 1 to 4.

Step 1 Create the employment status variable

The employment status variable has the following codes:

The procedure to derive the employment status variable from the answers to questions 1 to 3 is given in the following flow-chart.

Step 2 Create the self-coded occupation variable

On the basis of respondents' tick-box responses to question 4 create a variable with the following occupational codes.

Step 3 Derive NS-SEC

Once the employment status variable (step 1) and occupational variable (step 2) have been derived they are combined and an NS-SEC five-class code is assigned for each possible combination. The following matrix table assigns respondents to the appropriate NS-SEC five-class code. In the event of cases with missing information on either employment status or occupation, users may choose to impute missing values or treat these cases as missing data.

A file containing the cross-classification of employment status and occupation with the corresponding NS-SEC code in the form of a vector can be found here.

The resulting five-class NS-SEC classification is as follows: