STATISTICS

Analysing data

TYPES OF DATA

Quantitative data is data recorded with numbers – eg: learner’s weight or number of goals

Qualitative data is data recorded in words – eg: favourite colours

STATISTICAL GRAPHS OR CHARTS

Many different types of graphs (see page 254 and 255 in text book)

When graphs used incorrectly they can be very misleading …See website– http://www.coolschool.ca/lor/AMA11/unit1/U01L02

.htm#

Misleading graphs

Ways graphs/charts can be misleading:– Using 3D in pictograms/bar-charts– Using perspective/shape to exaggerate– Reversing the direction of an axis (to make a

decrease seem like an increase)– Altering the scale of the axis (to make it look more

or less steep)– Leaving part of the axis out to exaggerate

differences

DATA HANDLING

Mean (x) is like the average:

– Mean = sum of values

number of values

– Can be affected by outliers, so not a good measure of central tendency if outliers

…

Median is the one in the middle when placed in numerical order (smallest to biggest)– If there are outliers then median is a better

measure of central tendency

…

Mode is the value that appears the most (modal value)

Range = highest value – lowest value

USING A GROUPED DATA TABLE

Classes Tally Frequency

(f)

Midpoint (X)

fX(Frequency x

midpoint)

1-5 /// 3 (1+5)÷2=3 9

6-10 //// / 6 8 48

USING A GROUPED DATA TABLE

When the data has many different measurements involved in it, the data is usually grouped in intervals (classes)

Tally: lines used to count up the frequency of scores

Frequency is the number of times that score/value appears