Statistics Is the Collection and Analysis of Data in Order to Solve a Problem

Statistics Statistics is the collection and analysis of data in order to solve a problem.

Collecting Data

Fill in the blanks below by choosing words from the following list: Frequency Grouped Relevant Leading Difficult Biased

Meaning Pilot Width Collection Short Observation

Questionnaires often form part of surveys. The questions have to be very carefully designed to be of any use. If possible each question should be designed so that the respondent is required to tick a box.

 the ______of each question should be clear  questions should be ______.  ask ______simple questions  offer enough choices to cover all possible answers  avoid vague, personal questions which different people might interpret differently  do not try to persuade people to answer in a particular way - these are known as ______or ______questions  avoid asking embarrassing questions - people will not answer honestly.

A good idea is to test your questions on a few people first to see if some need to be changed or improved. This is known as a ______survey.

Decide how you will record your data

Before information is organised, it is called raw data.

You may collect data directly by counting or measuring and record this information on an ______sheet, also called a data ______sheet.

We can summarise data by drawing up a ______table. If there are a lot of different values for our data or we are using continuous data, you should use a ______frequency table.

The class interval is the ______of a group in a grouped frequency table.

When grouping your data, make sure:  You end up with between 5 and 10 groups  All class intervals are the same (except higher tier students)  Your groups cover all your data  No data can fall into two groups!  You try and use  and  to specify your groups

Example Lengths(cm) to be grouped: 12, 12,13,13,14,17,20,23,25,27,26,30,45,46,47,49,68

Lengths (l) in cm Tally Frequency 10  l  12 12  l  14 14  l  16 16  l  18 18  l  20 20  l  25 25  l  30 30  l  35 35  l  40 40  l  45 45  l  50

What is wrong with this grouped frequency table?

Tally marks are used in a frequency table to provide a way of sorting the data with the least chance for mistakes to be made. This is important. Make sure you know how to use them properly. You can practice by putting the data in the table above using tally marks. Types of Data

EXAMPLES Types home language English, French, Italian. of Data eye colour blue, green, brown. breeds of dog Dalmation, terrier, German Shepherd.

 Discrete data can assume only exact values  They are nearly always whole numbers.  They are mostly obtained by ______.

Examples:  number of cigarettes smoked per day...1, 2, 3 ... 20 ... 60 ...etc.  shoe sizes ... 5, 5½, 6, 6½, 7 ... etc.

 Always obtained by ______rather than counting  Can assume any real value  The precision depends on the accuracy of the measuring instrument

Examples:  height of birch trees in metres  length of human adult foot in centimetres  mass of 16-year-old female teenagers in kilograms