Graphs of Frequency Distributions 1) Frequency Histograms: BAR GRAPHS – Horizontal scale quantitative: measures data values – Vertical scale: measures FREQUENCIES of classes – Consecutive bars must TOUCH 2) Frequency Polygons:LINE GRAPHS – Line Graph: shows continuous change in frequencies – Horizontal & Vertical scales same as Histograms

Class Boundaries Used in HISTOGRAMS 1) Find the UPPER limit of FIRST class and LOWER limit of second class 2) Subtract these values (Usually 1) 3) Divide by 2 (Usually.5) 4) SUBTRACT this # from each lower limit and ADD this # to each upper limit: = boundaries

Frequency Distribution Histogram Class Boundaries are widths of bars Class Heights are the Frequencies of each class Frequency # of subscribers Internet usage

Frequency Distribution Polygons Midpoints of classes are x-values :extend ends Frequencies of classes are y-values: ends at 0 Connect points (line graph) Time online in minutes (midpoints) Frequency (# of subscribers)

Example: Do Try it Yourself p. 35 # 3 & 4 (Use data on p. 29) USE 6 Classes ClassClass Bound. TallyFreq.Mid. Pt.Rel. Freq. Cum. Freq.

Example: Do Try it Yourself p. 35 # 3 & 4 (Use data on p. 29) USE 6 Classes - Width (63-0)/6=10.5 ≈ 11 ClassClass Bound. TallyFreq.Mid. Pt.Rel. Freq. Cum. Freq

Example: Do Try it Yourself p. 35 # 3 & 4 (Use data on p. 29) USE 6 Classes - Width (63-0)/6=10.5 ≈ 11 ClassClass Bound. TallyFreq.Mid. Pt.Rel. Freq. Cum. Freq

Example: Do Try it Yourself p. 35 # 3 & 4 (Use data on p. 29) USE 6 Classes - Width (63-0)/6=10.5 ≈ 11 ClassClass Bound. TallyFreq.Mid. Pt.Rel. Freq. Cum. Freq

Example: Do Try it Yourself p. 35 # 3 & 4 (Use data on p. 29) USE 6 Classes - Width (63-0)/6=10.5 ≈ 11 ClassClass Bound. TallyFreq.Mid. Pt.Rel. Freq. Cum. Freq

Example: Do Try it Yourself p. 35 # 3 & 4 (Use data on p. 29) USE 6 Classes - Width (63-0)/6=10.5 ≈ 11 ClassClass Bound. TallyFreqMid. Pt.Rel. Freq. Cum. Freq IIII IIII IIII IIII IIII II IIII IIII III IIII IIII IIII I IIII II IIII IIII I III360 77

Example: Do Try it Yourself p. 35 # 3 & 4 (Use data on p. 29) USE 6 Classes - Width (63-0)/6=10.5 ≈ 11 ClassClass Bound. TallyFreqMid. Pt.Rel. Freq. Cum. Freq IIII IIII IIII IIII IIII II IIII IIII III IIII IIII IIII I IIII II IIII IIII I III

Histogram Frequency

Frequency Polygon Frequency