Even though there are other reasons employers find it difficult to fill vacancies, such as poor wages and working conditions, unattractive locations, limited career options and precarious contracts, the skills gap is often a real concern. Researchers view labour market mismatches as one factor in weak employment trends and sluggish productivity improvements. At times, the skills demanded by employers are simply not available, because the vocational training system is weak and/or unresponsive to labour market needs. However, this depends on adequate knowledge of a country's supply and demand for skills.