Table of means

The row axis for this table was as follows. The meaning of each statement is explained in Introduction to axes.

l q7
n01Age of Car;c=c121'1/4';inc=c121
n01Price;c=c122'1/4';inc=c122
n01Availability of Spare Parts;c=c123'1/4';inc=c123
n01Reputation of Manufacturer;c=c124'1/4'';inc=c124
n01Mileage;c=c125'1/4';inc=c125
n01Sound Bodywork;c=c126'1/4';inc=c126
n01Reputation of Dealer;c=c127'1/4';inc=c127
n01Extras (for example Radio);c=c128'1/4';inc=c128

If a ‘1’ in a column means that the item is not important, and a ‘4’ in that column means that it is very important, the total mean value for the first row (3.10) shows that people think the age of the car is quite important when buying a secondhand car.

Because of the rounding involved in calculating means, it is important that you specify the number of decimal places that will provide the level of accuracy that you require. In this example, the keyword dec= on the tab statement has been used to specify two decimal places.

Note Statistical tests on means specified by the means option are likely to give inaccurate results. If you want to request a statistical test on mean values, specify the mean by using an n12 statement. For more information, see Mean, standard deviation, standard error and error variance.

Q7: Importance of Each of the Following
When Buying a Secondhand Car
Sex Age
Total Male Female Over 30 Under 30

MEAN IMPORTANCE

Age of Car 3.10 3.17 3.00 2.60 3.60

Price 1.90 1.83 2.00 1.40 2.40

Availability of 2.80 2.83 2.75 2.40 3.20
Spare Parts

Reputation of 1.90 2.17 1.50 1.60 2.20
Manufacturer

Mileage 3.10 3.33 2.75 3.00 3.20

Sound Body 2.20 1.83 2.75 2.40 2.00

Reputation of 3.30 3.17 3.50 3.20 3.40
Dealer

Extras (for example Radio) 1.70 2.00 1.25 2.00 1.40

Tables of the maximum or minimum values of inc variables can be generated in the same way by replacing the keyword means on the tab statement with maxim or minim as appropriate.

The keywords minim and maxim are also valid on individual statements in an axis. When used in this way they create an element that shows the minimum or maximum values of the inc= variable specified for that element. Here is an axis that creates three elements. The first is the minimum price paid, the second is the maximum price paid, and the third is the mean price paid (the n25 does not create a printed element):

l price
n01Minimum price paid;inc=paid;minim
n01Maximum price paid;inc=paid;maxim
n25;inc=paid
n12Mean price paid