Chapter 7:Data Collection and PresentationMathematics DepartmentCorpus Christi School

When you want to buy a phone, which brand will

you buy? Apple or Samsung?

StatisticsA branch of Applied MathematicsInvolves in collection, organization, presentation, and interpretation of data.

StatisticsStatistics involves:Data Collection;Data Presentation; andDescribing the data collected

What are Data?Data is collected from two main sources:1. Population2. Sample

Example 1A pharmaceutical company wishes to monitor their products. A. The population for this study is the totality of all medicinal drugs produced by the company.B. The sample would be all the drugs examined for quality control on a particular day.

Example 2A polling firm wishes to determine the voting preferences of Filipino voters for the next election A. The population for this study is the totality of all Filipinos of voting age.B. The sample would consists of all voters surveyed by the firm.

Example 3A survey is being conducted to determine the TV viewing preferences of Filipino HS students. A. The population consists of all Filipino HS students.B. The sample consists of HS students included in the survey.

Therefore:A. Population – totality of all individuals or objects from which the required information is to be obtained.B. Sample – a subset or part of the population.

Variable- Is the particular information of interest to be obtained from either the population or sample.

Example 1A pharmaceutical company wishes to monitor their products.

The variable is the number of percentage of products passing the quality control test

Example 2A polling firm wishes to determine the voting preferences of Filipino voters for the next election

The variable is the voting preference of the Filipino voters

Example 3A survey is being conducted to determine the TV viewing preferences of Filipino HS students.

Some of the variables that may be studied include favourite television shows, preferred genre, and number of hours.

Review:PopulationSampleVariableData

Observation/Scores-The values of the variable

Example 4If the variable of interest is favourite sports.

Some of the values are basketball, swimming, tennis, taekwondo, badminton and archery

Example 5If the variable of interest is number of hours of sleep.

Some of the values are 6, 7, and 8.

Example 6If the variable of interest is number of siblings.

Some of the values are 0, 1, 2, and 3.

Types of Variables1. Qualitative – variables that measure quality or characteristic.

Ex. Hair Color, Gender, Religion

2. Quantitative – variables that measure a number or an amount.a. Discrete – obtained by countingb. Continuous – obtained by measuring

Classify the ff:NationalityWeightCredit LimitVoting PreferenceHair ColorTemperatureShirt size

Identify a possible sample:

1. Students enrolled in schools in Cagayan de Oro2. Electric consumption in Cagayan de Oro3. Philippine Dialects4. Religions of the World5. Average salaries of employees in the Philippines

Identify the Variable of interest1. Survey to determine the choice of president for first time Filipino Voters

2. Study to determine the career-preferences of graduating Filipino High School Students

3. Study to determine the leading causes of death among Filipino Males

4. Survey to determine the most preferred movie genre of Filipinos

Identify the Variable of interest

Descriptive – concerned with describing the characteristics and properties of a group of person, places or things.

Division in Statistics

Inferential – is used to draw inferences, prediction, conclusion and information about the properties or characteristics of a large group from the information from the small group.

Division in Statistics

Identify the division of Statistics:

1. A teacher computes the average grade of her students and then determines the top ten.2. A manager of business firm predicts future sales of the company based on the present sales.

Identify the division of Statistics:

3. A psychologist investigates if there is a significant relationship between mental age and chronological age.4. A researcher studies the effectiveness of a new fertilizer to increasing food production.

Identify the division of Statistics:

5. A school administrator forecasts future expansion of a school.

Is any numerical or nominal characteristic of a population. It is a value or measurement obtained from the population.

Parameter

Is an estimate of a parameter. It is a value or measurement obtained from a sample.

Statistic

1. Discrete Variable2. Continuous Variable3. Dependent Variable4. Independent Variable

Classifications of Variable

Obtained from countingEx. Number of students in 1I is 30.

Discrete Variable

Obtained through measuringEx. Height of a Building

Continuous Variable

A variable which affects or influences the dependent variable.

Independent Variable

The variable which is affected or influenced by another variable

Dependent Variable

A study to determine the favorite brand of shoes of Corpus Christians

IV – Quality of shoes, price of shoes, design, size, colorDV - Brand

1. Nominal Scale2. Ordinal Scale3. Interval Scale 4. Ratio Scale

Scales of Measurement

The assignment of symbols or numerals to objects or events.

Measurement

It is used when we want to distinguish one object from another for identification purposes.Ex. Gender, Religion

Nominal Scale

Data or measure arranged in some specified rank.Ex. Beauty Contest, Runners

Ordinal Scale

Used when we can say that the object is greater or lesser but we can also specify the amount of difference.Ex. Scores in a Test, Grade

Interval Scale

It is like the interval unit. This is only used when one object is so many times as large or small as the other.Ex. The weight of the mother is twice as her daughter.

Ratio Scale

Identify the scale of measurement:

1. Religion2. IQ Scores3. Speed of a Car4. Civil Status5. Address6. Size of T-shirt7. Salary of workers