Data Collecting, Organizing & Analyzing. VARIABLES & DATA TABLES.

Data Collecting, Organizing &

Analyzing

VARIABLES & DATA TABLES

In an experiment there are 2 types of variables• INDEPENDENT VARIABLES

&

•DEPENDANT VARIABLES

a VARIABLE is any factor, or thing that can change during your experiment

a CONTROLED experiment only has 1 variable changing, or being tested

Sometimes a control trial or group is used to compare experimental data to

INDEPENDENTVARIABLE

This is the variable we can control in an experiment.

Independent variables are set up ahead of time, before you start following your procedures

INDEPENDENTVARIABLE

In a “T” table, or data table, this variable is on the left side.

On a graph, this variable goes on the X axis

INDEPENDENT VARIABLE Examples of common

Independent variables:• Time-measure every 30

seconds, every day, etc.• Distance-measure every 0.5

meters, every 10.0 cm• Amount-add 2.0 grams each

trial

INDEPENDENTVARIABLE

Your book calls the independent variable the MANIPULATED variable, because we manipulate or set it to our specifications

DEPENDENTVARIABLE

This is the variable we have to observe in an experiment.

Dependent variables are measured during the experiment, after you start following your procedures

DEPENDENTVARIABLE

In a “T” table, or data table, this variable is on the right side.

On a graph, this variable goes on the Y axis

DEPENDENT VARIABLE Examples of common

Dependent variables:• Temperature-record the

temperature• Mass-find the mass of each

object or substance• Amount-count the resulting

number of items

DEPENDENTVARIABLE

Your book calls the dependent variable the RESPONDING variable, because it responds to the procedure you are following. We can’t chose what the data will be.

GRAPHING NOTES

7 RULES OF GRAPHING

Follow these simple rules for GREAT GRAPHS

RULE # 1.

1. Always draw neat lines with a straight edge or ruler

RULE # 2. Make your graph 1 full page

in size. Small graphs are too difficult

to read patterns or results of your experiment.

RULE # 3. Label the x-axis (goes across

the bottom of your graph) Label the y-axis ( the line that

goes up & down on the left side of your graph)

RULE # 4. Label three places on your

graph. 1. TITLE the graph

descriptively WHAT DOES YOUR

GRAPH SHOW US?

RULE # 4. 2. label the x-axis with the

independent variable• this is the variable you pre-set before

you began collecting data, on the left side of a “T” table

• common independent variables can be time, or distances

• Data points should be evenly spaced

RULE # 4. 3. label the y-axis with the dependent

variable• this is the variable you measure when

you begin collecting data, on the right side of a “T” table

• common dependent variables can be mass, or temperature

• Data points should be evenly spaced

RULE # 5. Number the x and y axis with

a regular numerical sequence or pattern starting with 0 to space out your data so it fills the entire graph• examples: 0, 5, 10, 15 . . .

• 0, 2, 4, 6, . ., 0, 0.5, 1.0, 1.5, 2.0

RULE # 6. Number the x and y axis on

the lines of the graph, not the spaces between the lines

RULE # 7. If your graph shows more

than one trial of data, or has more than 1 line, USE A KEY

A key can be different colored lines, lines with different textures or patterns.

Choose the best graph for the data

Pie chart- shows percentages and parts of a whole

Bar graph- best for comparing data Line graph- best for looking at change over

time Stem & Leaf plot- comparing data that can

also show mean, mode, and median

Statistical Analysis Mean- (average)- add up all the data & divide that

total by the number of data points ex. : 1,2,3,2,4,2 = 14 14/6= 7/3 or 2.3

Mode- number seen most often ex:1,2,3,2,4,2 mode is 2

Median- middle value when data is placed in numerical order Ex.: 1,2,2,2,3,4,5 odd

ex:1,2,2,2,3,4 even 2+2=4/2=2 median is 2 Range- difference between the greatest # and the

smallest # in the data set ex.1,2,2,2,3,4 4-1= 3 data vary over 3 values

How to change numbers into % for pie charts. You can refer to your book on page 770. Determine the total number for your data: add up all the

values to get one number. 1,2,2,2,3,4 = 14 Divide each proportion by the total number. 1/14, 2/14.

3/14, 4/14 Multiply that decimal by 360. This will give the number

of degrees that your pie piece should contain. Ex. 2/14= 0.143 0.143 x 360= 51.4 degrees

Use a protractor to measure the angle of each slice. To find the percentage take the number of degrees in the

slice divide it by 360 and multiply the new number by 100%. 51.4 / 360= 0.143 x 100% = 14.3 %

The EndGood Luck and Happy Data

Collecting!