4 To picture "penod' doto as ogomst "point" doNi.

5 For s>iowir^ o rar>ge of volues or deviations from a normal or bogey.

C THE COIUMN CHART IS NOT THE BEST FORM:

1. For comporing several times senes

2. For lime series over an eilended period with many plottings

1. LAYOUT AND DESIGN A chon consisting of o few columns should generoify be higher than wide, for more than a few columns a widerthon-high chort is preferoble

2 GRIDS. T)>e field or grid used for column charts may be a completely ruted coordirtote surfoca. Usuolly. however, il is not necessary to lrtd<ose all the rulirigs which would normally be shown on o line chon. A complete grid outline is usually not reauired The columns It^ewsehres generally moke vertKol rulings unnecessory. Moreover, (ewer )>ori2ontol rulings may be needed since column chorts ore more gerwrally used for popular presentation thon are line chorts. Often horizontal rulir>gs may be incomplete, being extended through only that portion of the field occup«d by the columns.

3. SCAIE SELECTION In column chorts the interest is generolly in a comparison between amounts os of different dotes. These amounts ore proportionote to the height of the columns This means Ihot the zero line, when it is ifie prir>cipot hne of reference, should olwoys be iTKluded in a column chort. It follows, too, that the omouni scoles should no* be broken, but mode continuous from the reference Ime. While normoffy the full length of the column should be shown, when it represents on abr<ormally lorge value the column may be broken at the lop ond ttie omount irKitcoted.