More about percentiles
Results from the Lexplore assessment are given as an overall percentile within five different reading levels on a normal distribution curve.
Normal distribution curves are used frequently in many different contexts, not just within education. Data is normally distributed when it is symmetrical around a central value, the mean, median and mode of the data set. When compiled in a histogram this data set forms the normal distribution or bell curve below. This curve appears like a hill with different peaks depending on the standard deviation.
The mean is always in the centre of the curve; the greater the distance between the mean and any point, the further away from the mean it is. Half of those within the distribution will be lower than the average and half will be higher. The largest group therefore lies in the middle of the curve groups then become smaller the further you move in either direction from the mean.
As many assessments only look at the reading components in isolation of one another it can be difficult for teachers to pinpoint exactly which area of reading a child is struggling with. By measuring how the reading components work together, we can offer teachers a new and objective analysis of a child’s natural reading ability by incorporating all the main cognitive processes involved. Each pupil’s overall result can then be broken down within the Results Portal into their individual components to highlight specific areas needing support and provide a more granular analysis.
Each group within the normal distribution can be divided into percentile values. These range from 0 to 100 and give a much more precise picture of where a pupil lies in relation to the entire data set. At the 75th percentile, for example, 75 % of the group falls below and the other 25 % over. The central (Average) group of the Lexplore normal distribution is for those pupils with a percentile score between 26 and 75. When it comes to monitoring progress throughout the year, repeat testing might result in pupils remaining within the same reading level, but their percentile score may indicate small progressions or regressions within that group. As the Lexplore assessment is able to take into account the natural progressions a pupil makes through the year, even those remaining on the same percentile scores will have progressed as expected for their specific age group.