Ideally, but not necessarily, the open and close should be equal. While a doji with an equal open and close would be considered more robust, it is more important to capture the essence of the candlestick. Prices move above and below the opening level during the session, but close at or near the opening level. The result is a standoff. Neither bulls nor bears were able to gain control and a turning point could be developing.
Different securities have different criteria for determining the robustness of a doji.
Determining the robustness of the doji will depend on the price, recent volatility and previous candlesticks. Relative to previous candlesticks, the doji should have a very small body that appears as a thin line. Steven Nison notes that a doji that forms among other candlesticks with small real bodies would not be considered important. However, a doji that forms among candlesticks with long real bodies would be deemed significant. The relevance of a doji depends on the preceding trend or preceding candlesticks.