CES Peak-Trough Tables


    Peak-trough tables produced by the BLS Current Employment Statistics (CES) program identify key turning points in seasonally adjusted CES time series. Key turning points are those which mark the beginning of sustained periods of growth or contraction in the time series. These points mark changes in trend and are distinct from month-to-month or other short-term fluctuations.

    Current peak-trough tables for published CES time series

    CES peak-trough tables designate the following cyclical phases in CES time series:

    • A peak marks a cyclical high point in a time series, although there may be higher points in the time series’ history.
    • A trough marks a cyclical low point in a time series, although there may be lower points in the time series’ history.
    • A contraction in a time series is the period of decline from a peak to a trough.
    • A recovery in a time series is the period of growth from the trough to the point where the series equals or first exceeds the prior peak.
    • An expansion in a time series is the period of growth following a recovery.


    Cyclical phases in time series


    Peaks and troughs are designated according to the following criteria:

  • Periods between peaks and troughs--known as phases--must be of at least 6 months in duration.
  • Periods between one peak and the next, or between one trough and the next--known as cycles--must be of at least 15 months in length.
  • Neither a peak nor a trough can be designated in the table’s first or last 5 months.
  • Any irregular (not seasonal) and quantifiable changes are removed prior to calculating peaks and troughs.
  • The peak in a given cycle must be higher than any other point in the cycle, excluding irregular (not seasonal) and quantifiable changes (such as temporary intermittent decennial census workers).
  • The trough must be lower than any other point in the cycle, excluding irregular quantifiable and temporary changes (such as strikes).
  • Peaks and troughs must occur in alternating order.
  • It is important to note that the peaks and troughs identified in a CES time series are specific to that particular time series. Although turning points in CES data frequently coincide with or occur near cyclical turning points in the overall economy, this is not always the case. (Note: Economy-wide turning points are identified by the National Bureau of Economic Research (NBER). For more information, including a complete list of business cycle dates, consult the NBER webpage at http://www.nber.org/cycles/main.html.)

    Guide to the peak trough table

    At the top of each peak trough table is a heading listing the release date of the data in the table, the industry title, NAICS code (when applicable), and the type of data appearing in the table.

    Months are displayed across the top of the table and years appear along the left side.

    A: For each month, both the level of the data and, underneath it, the over-the-month change in that level are displayed.

    B: If a month is designated as a peak or a trough in the time series, that is indicated by the word "PEAK" or "TROUGH" being displayed between the level and the over-the-month change.

    C: A solid line indicates a high point or a low point in the data, for the time period displayed in the table. When a high or low point coincides with a peak or trough, these lines appear as underscores beside the word "PEAK" or "TROUGH."

    D: An "S" next to the over-the-month change indicates that the series was adjusted for an irregular movement, such as a strike.

    E: "P" indicates that data is preliminary and subject to future revision.

    Guide to CES peak-trough table


    Last Modified Date: December 10, 2012