Understanding the Spine Charts

The following indicators are presented in spine charts which show how much the practice and the PCT scores differ from the London mean. The actual values for each indicator are provided in the left hand column and the values for all practices in the PCT, alongside the meta-data can be obtained by clicking on each indicator name. If the practice score is statistically different to the London mean then the practice circle is coloured as per the legend below. Further information can be found in the guidance document.

The z-score for each practice for a given indicator is calculated on the assumption that the practice values for that indicator follow a statistical normal distribution. For some indicators included in the profiles, the distribution of practice values may differ from normal and the use of z-scores in such cases is imperfect.

• Practice value: statistically worse performance or higher need than the London average
• Practice value: similar to the London average
• Practice value: statistically better performance or lower need than the London average
• PCT value
• Range of values for all practices within the PCT

Click on the name of an indicator on the spine chart to see the metadata for the indicator and a chart showing all practices within the PCT. Data can be downloaded by clicking on the download link.