12. Technical note

Coverage

Information regarding labour disputes within the UK is collected by Office for National Statistics (ONS) from a variety of sources. The information is collected directly from the employer or trade union involved after we have identified disputes from press reports. We publish figures on labour disputes each month in the Labour market statistical bulletin.

Definition of stoppages

The statistics cover stoppages of work in progress in the UK during a year caused by labour disputes between employers and workers, or between workers and other workers, connected with terms and conditions of employment. A distinction can be drawn between stoppages that started in the current year and those that started in earlier years.

A stoppage in progress is defined as a dispute that has continued from a previously recorded dispute by the same organisation and for the same cause. Prior to 2015, a dispute was counted as a new stoppage if there was a gap of more than one month between instances of industrial action. From 2015, disputes with a gap of more than one month between instances of industrial action are counted as a single stoppage.

The statistics exclude disputes that do not result in a stoppage of work, for example, work-to-rules and go-slows; this is because their effects are not quantifiable to any degree of certainty. Stoppages involving fewer than 10 workers or lasting less than one day are also excluded unless the total number of working days lost in the dispute is 100 or more.

Stoppages over issues not directly linked to terms and conditions between workers and employers are omitted, although in most years this is not significant. For example, in 1986 one stoppage was considered to be political (a protest in the coal industry against the visit of an MP) and it was excluded from the figures. The total working days lost amounted to less than 1,000. The next known dispute to be excluded was in 1991. This involved a boycott by self-employed market traders who, after increased rent and changes to the market rules, kept their stalls closed for about 20 weeks.

The statistics include “lock-outs”, that is, where an employer prevents their employees from working by refusing entry to the place of work and “unlawful”, that is, unlawfully-organised strikes. However, no distinction is made between a “strike” and a “lock-out” or between “lawful” and “unlawful” stoppages. This is principally because of the practical difficulty in deciding in which category a particular stoppage falls. It was for similar reasons that a distinction between “official” and “unofficial” disputes was no longer made after 1981.

Working days lost

Working days lost are defined as the number of days not worked by people as a result of their involvement in a dispute at their place of work. In measuring the number of working days lost, account is taken only of the time lost in the basic working week. Overtime work is excluded, as is weekend working where it is not a regular practice.

Where an establishment is open every day and runs two or more shifts, the statistics will record the number of working days lost for each shift. In recording the number of days lost, allowance is made for public and known annual holidays, such as factory fortnights, occurring within the strike's duration. No allowance is made for absence from work for such reasons as sickness and unauthorised leave.

Where strikes last less than the basic working day, the hours lost are converted to full-day equivalents. Similarly, days lost by part-time workers are converted to full-day equivalents. The number of working days lost in a stoppage reflects the actual number of workers involved at each point in the stoppage. This is generally less than the total derived by multiplying the duration of the stoppage by the total number of workers involved at any time during the stoppage, because some workers would not have been involved throughout.

In disputes where employers dismiss their employees and subsequently reinstate them, the working days lost figure includes those days lost by workers during the period of dismissal.

For disputes where employers dismiss their employees and replace them with another workforce, the statistics cannot assume that working days lost by the sacked workers continue indefinitely. In such cases, the statistics measure the number of days lost in terms of the size of the replacement workforce. For example, where an employer initially recruits 100 workers and wishes to build up to 300, the number of working days lost on the first day will be 200 and will then progressively reduce on subsequent days, eventually to zero when the new workforce reaches the target of 300.

Figures given for working days lost per 1,000 employees use employee jobs for each year taken from our most recent estimates of workforce jobs.

Number of stoppages

There are difficulties in ensuring complete recording of stoppages, in particular for short disputes lasting only a day or so, or involving only a few workers. Because of this recording difficulty and the cut-off applied, the number of working days lost is considered to be a better indicator of the impact of labour disputes than the number of recorded stoppages.

Workers involved

We aim to record the number of workers that are involved at any time in the stoppage. For example, consider a three-day strike where there were 200 workers involved on the first day; 300 on the second day, of whom 100 were involved for the first time; and 200 on the third day, of whom 50 were involved for the first time. The total number of workers involved in the dispute is 350 – the sum of all those involved on the first day and those joining for the first time on subsequent days.

However, the number of workers taking strike action for the first time during a dispute cannot always be easily ascertained. In such cases, the statistics record the highest number involved at any one time (300 in this example).

Take another example, where there are 200 workers involved in a stoppage on each of days one, two and three. It may be necessary to assume that there were a total of 200 workers involved, although it is possible, but unlikely, that as many as 600 workers could have been involved. For this reason, the statistics may under-estimate the number of workers involved in a dispute. However, the estimate of the number of working days lost is unaffected by this consideration.