Data ManagementGrade 7

What’s the Story?Secondary data is information that was collected by someone else. Referring to information that was published in a book or made available online is an example of secondary data.

Primary data is data that is collected directly. If YOU design, distribute and record the results of a survey, the information you gather is called primary data.

Examine

Graphs, data and statistics are a math tool for organizing and analyzing large amounts of

information, i.e., data helps to tell a story.

Men vs. WomenIs the “women and children first” rule

fair?

Census vs. SampleCensus

First I asked the whole class

The whole

Everyone

Sample Next I asked just the girls

A portion

A small amount of people that fit a certain category

Bias

Checking for bias in data collection

Data from experiments, survey questionnaires and interviews can be influenced by either the context of the study, the respondents themselves, or the researcher.  The term "bias,” technically meaning "leaning" in one direction, it is often used to refer to respondents or researchers having pre-conceived ideas or an ideological disposition.  What we mean here by bias is anything that can "contaminate" the picture you are trying to get of either subjects' behaviour or their attitudes and beliefs.

To influence in an unfair way; "you are biasing my choice by

telling me yours.”

A partiality that prevents objective consideration of an

issue or situation or cause to be biased.

Designing and Conducting a Valid Survey

Your Task:Think about why you want to collect data, e.g.,

music at a dance, fundraising, school uniforms…

In groups of 2-3, decide on a topic for which you would like to collect data and design a survey.

You must consider bias, sample size, phrasing of the question and method of data collection when designing your survey.

Answer the Following Questions before

Surveying:How will the information collected be used?

How and why is this important?

What collection methods will be used?

What is an appropriate sample size?

Are questions appropriately phrased?

How does data management help you become an informed decision maker?

Organizing, Displaying and Presenting Data

Interpret, display, graph and draw conclusions from primary data.

Frequency Table

A frequency table is a table that lists items and uses tally marks to record and show the number of times they occur.

This frequency table shows the number of grade 2 students who chose Taco or Burger as

their favorite bakery food.

Stem and Leaf Plot

-suppose you have the following list of values: 12, 13, 21, 27, 33,

34, 35, 37, 40, 40, 41.

-The "stem" is the left-hand column which contains the tens

digits.

-The "leaves" are the lists in the right-hand column, showing all the ones digits for each of the

tens, twenties, thirties, and forties.

As you can see, the original values can still be determined; you can tell, from that bottom

leaf, that the three values in the forties were 40, 40, and 41.

Bar Graphs Bar graphs are an

excellent way to show results that are one time, that aren't continuous - especially samplings such as surveys, inventories, etc.

This is a typical survey asking students about their favorite after school activity. Notice that in this graph each column is labeled.

Line Graphs A line graph is most

useful in displaying data or information that changes continuously over time.

The example here shows the changes in the temperature over a week in January. Notice that the title of the graph is "Average Daily Temperature for January 1-7 in degrees Fahrenheit".

Circle/Pie Graphs Circle or pie graphs are

particularly good illustrations when considering the parts of a whole.

In the example, both the number of hours in a whole day devoted to certain activities is listed as well as the percent of time for each of these activities.

Presentation of Primary Data

Share the results of your survey with the class.Create a presentation of chart paper that includes

a frequency table, an appropriate graph, an a clear survey question.

CriteriaQuestion and purpose of the survey is clearly

stated

You can explain how you attempted to eliminate bias

Frequency table is clearly displayed

All parts of the graph are clearly labeled

The graph summarizes the results

Presentation should be 2-3 minutes in length