Wynberg girls high-Jade Gibson-maths-grade9-statistics analysing data

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Statistical analysis of data

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Wynberg girls high-Jade Gibson-maths-grade9-statistics analysing data

  1. 1. STATISTICS Analysing data
  2. 2. TYPES OF DATA <ul><li>Quantitative data is data recorded with numbers </li></ul><ul><ul><li>eg: learner’s weight or number of goals </li></ul></ul><ul><li>Qualitative data is data recorded in words </li></ul><ul><ul><li>eg: favourite colours </li></ul></ul>
  3. 3. STATISTICAL GRAPHS OR CHARTS <ul><li>Many different types of graphs (see page 254 and 255 in text book) </li></ul><ul><li>When graphs used incorrectly they can be very misleading …See website </li></ul><ul><ul><li>http://www.coolschool.ca/lor/AMA11/unit1/U01L02.htm# </li></ul></ul>
  4. 4. Misleading graphs <ul><li>Ways graphs/charts can be misleading: </li></ul><ul><ul><li>Using 3D in pictograms/bar-charts </li></ul></ul><ul><ul><li>Using perspective/shape to exaggerate </li></ul></ul><ul><ul><li>Reversing the direction of an axis (to make a decrease seem like an increase) </li></ul></ul><ul><ul><li>Altering the scale of the axis (to make it look more or less steep) </li></ul></ul><ul><ul><li>Leaving part of the axis out to exaggerate differences </li></ul></ul>
  5. 5. DATA HANDLING <ul><li>Mean (x) is like the average: </li></ul><ul><ul><li>Mean = sum of values </li></ul></ul><ul><ul><ul><ul><li>number of values </li></ul></ul></ul></ul><ul><ul><li>Can be affected by outliers, so not a good measure of central tendency if outliers </li></ul></ul>
  6. 6. … <ul><li>Median is the one in the middle when placed in numerical order (smallest to biggest) </li></ul><ul><ul><li>If there are outliers then median is a better measure of central tendency </li></ul></ul>
  7. 7. … <ul><li>Mode is the value that appears the most (modal value) </li></ul><ul><li>Range = highest value – lowest value </li></ul>
  8. 8. USING A GROUPED DATA TABLE 48 8 6 //// / 6-10 9 (1+5) ÷2= 3 3 /// 1-5 fX (Frequency x midpoint) Midpoint (X) Frequency (f) Tally Classes
  9. 9. USING A GROUPED DATA TABLE <ul><li>When the data has many different measurements involved in it, the data is usually grouped in intervals (classes) </li></ul><ul><li>Tally : lines used to count up the frequency of scores </li></ul><ul><li>Frequency is the number of times that score/value appears </li></ul>

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