Analysing results and using percentiles

• For an organism to function, substances must move into and out of cells.
• Three processes contribute to this movement – diffusion, osmosis and active transport.
• Part of Biology (Single Science) Cell biology
• There are several methods of finding a percentile, the simplest being the nearest rank method.
• The concentration of close solutes in the cells of the potato in this investigation is 0.27 mol dm -3 , where the line crosses the x-axis.
• Scientists use percentiles to divide a set of data into 100, and look to see where the data lie within these divisions.
• The concentration of dissolved solutes in the cells of different potatoes will vary slightly from potato to potato.
• The 50th percentile is the median, the point in a set of data where 50 per cent of the data fall above this value, and 50 per cent below it.
• A set of data for a range in concentrations can be analyzed by looking at the range, the mean, and the median, but these do not show whether data is evenly spread or whether it is clustered together within a certain range.
• To find the percentile using the nearest rank method, the data must first be put into order.
• The 75th percentile is where 75 percent of the data fall below this value.
• For a range of values for the concentration of potato cell sap, the 50th percentile is 0.27 mol dm -3.
• For the student's value of 0.27 mol dm -3, the percentile rank is 47th percentile.
• The 50th percentile can be found by arranging the values in order and finding the rank, where the ordered rank is not a whole number, the number is rounded up.
• The 50th percentile is found by arranging the values in order and finding the rank, which is the ordered rank.
• To find the percentile rank of a value, x, the formula is: percentile rank = (B + 0.5E)/n × 100, where B is the number of values below x, E is the number of values equal to x, and N is the number of values.
• For another student's value of 0.29 mol dm -3, the percentile rank is 70th percentile.
• The 90th percentile for the same set of data is 0.32 mol dm -3 and is found by arranging the values in order and finding the rank, where the ordered rank is not a whole number, the number is rounded up.
• The percentile rank shows the position of a value within a range.