#Range on box and whisker plot how to

There is one graph that is mainly used when you are describing center and variability of your data.

As a rule of thumb, observations can be qualified as outliers when they lie more than 1.5 IQR below the first quartile or 1.5 IQR above the third quartile.

It might still be useful to look for possible outliers in your study.

Test Scores (as ) for 9th Period 38 72 88 96 102 1.

The main advantage of the IQR is that it is not affected by outliers because it doesnР Р†Р вЂљРІвЂћСћt take into account observations below Q1 or above Q3. Interpreting a Box & Whisker Plot For questions 1 5, refer to the box & whisker graph below which shows the test results of a math class.

The interquartile range is Q3 minus Q1, so IQR = 6.5 Р Р†Р вЂљРІР‚Сљ 3.5 = 3. Again, since the second half of the data set has an even number of observations, the middle value is the average of the two middle values that is, Q3 = (6 + 7)/2 or Q3 = 6.5. Q3 is the middle value in the second half of the data set. Since there are an even number of data points in the first half of the data set, the middle value is the average of the two middle values that is, Q1 = (3 + 4)/2 or Q1 = 3.5. Q1 is the middle value in the first half of the data set. Example:Р вЂќР’В¬onsider the below example to get clear idea.Р вЂќР’В¬onsider another example to get better understanding.Р вЂќР’В¬onsider the following numbers: 1, 3, 4, 5, 5, 6, 7, 11. Steps 5: Now subtract Q1 from Q3 to get IQR. Steps 4: Similarly find Q3 by looking the median of the right of Q2 Step 3: Then find Q1 by looking the median of the left side of Q2 Step 2: Find the median or in other words Q2 The interquartile range is the distance between the third and the first quartile, or, in other words, IQR equals Q3 minus Q1 First 25% is 1 st quartile (Q1), last one is 3 rd quartile (Q3) and middle one is 2 nd quartile (Q2).Р вЂќРЎС› nd quartile (Q2) divides the distribution into two equal parts of 50%. It equally divides the distribution into four equal parts called quartiles. It is a better measure of dispersion than range because it leaves out the extreme values. Interquartile range gives another measure of variability. In this case, you can go for another measure of variability called interquartile range (IQR). It is the difference between the highest and the lowest value.Р вЂќР вЂћs ranges takes only the count of extreme values sometimes it may not give you a good impact on variability. The most simple measure of variability is the range.

Box Plot to get good indication of how the values in a distribution are spread out.

In this situation measures of variability comes into picture. This indicates that, if you adequately describe a distribution some time it may need more information than the measures of central tendency. If you consider both the team their Mode= 14.1, Median=15 and Mean=15 Sometimes it may happen that mean, median, and mode are same for both groups. Mean, Median and Mode for both the groups. You have already calculated the central tendency of your data i.e. I have used the same data set as above in this article.LetР Р†Р вЂљРІвЂћСћs think, in certain cases, you are comparing two groups. First, let us look at a very simple example. You can create a BOX Plot in SAS using the SG PLOT procedure.

#Range on box and whisker plot how to

Q1 Р Р†Р вЂљРІР‚Сљ 1.5 * IQR How to create a Box and Whisker plot in SAS?

Similarly, if a value is lower than the 1.5*IQR below the lower quartile (Q1), the value will be considered an outlier. Outlier: If a data point is higher than the 1.5*IQR above the upper quartile (Q3), the value will be considered an outlier.

Interquartile range (IQR): It is the box plot showing the middle 50% of scores and can be calculated by subtracting the lower quartile from the upper quartile (e.g. Negatively Skewed: When the median is closer to the upper quartile (Q3) and the whisker is shorter on the upper end of the box, then the distribution is negatively skewed. Positively Skewed: When the median is closer to the lower or bottom quartile (Q1) then the distribution is positively skewed. Normal Distribution or Symmetric Distribution: If a box plot has equal proportions around the median and the whiskers are the same on both sides of the box then the distribution is normal.