Science Fair Research Paper Notes
Classifying Data
A. Dependent variables can be classified as quantitative or qualitative.
a. Quantitative data is based on measurements made using a scale with
equal intervals.
i. Height of a person in meters, mass of rabbits in kilograms,
temperature of water in degrees Celsius.
b. Qualitative data is collected using non-standard scales with unequal
intervals or discrete categories.
i. Gender of an organism, color of an individual’s eyes.
c. Quantitative and qualitative data can be further subdivided based on
the level of measurement.
B. Quantitative Data
a. Ratio Data – Quantitative data that is collected using a scale with
equal intervals and an absolute zero.
i. Temperature of gas on the Kelvin scale, velocity of an object in
m/sec, the distance from a point in meters.
b. Interval Data – Quantitative data that is collected using a scale with
equal intervals, but no absolute zero.
i. Temperature of a substance on the Celsius scale. (Water
molecules are still moving at 0 Celsius, dates, time.
C. Qualitative Data
a. Nominal Data – Qualitative data that is collected when objects have
been named or placed into discrete categories that cannot be ordered.
i. Gender and hair color are two examples.
b. Ordinal Data – Qualitative data that is collected when objects are
placed into categories that can be rank ordered.
i. An activity that could be rated on a scale of 1 to 5.
Refer to Scenario: “Mary”
Dependent
Variable
Height of Plants
Health of Plants
Leaf Quality
Type of Data
Level of
Measurement
Explanation
Quantitative
Qualitative
Qualitative
Ratio
Nominal
Ordinal
Equal Int., Abs. Zero
Discrete, Not Ranked
Discrete, Ranked
Describing Data
D. Measures of Central Tendency
a. Mean – The average or sum of the individual values divided by the
number of values. This can only be calculated for interval or ratio
data.
i. Find the mode of this data.
7
15
10
6
13
10
5
12
8
5
11
7
4
9
7
3
9
5
Mean=
Mean=
Mean=
b. Median – The middle value, after all of the cases have been rank
ordered from highest to lowest. This can only be calculated for
ordinal, interval, or ratio data but not with nominal data.
i. Calculate the median of the above data.
Median=
Median=
Median=
c. Mode – The value of the variable that occurs most often. This can
only be used for nominal, ordinal, interval, or ratio levels.
i. Calculate the mode of the above data.
Mode=
Mode=
Mode=
E. Measures of Variation
a. Range – The value that is calculated by subtracting the smallest value
from the largest value. This can only be used with quantitative data.
Range=
Range=
Range=
b. Frequency Distribution – Shows the number of cases that falls into
each category. This can only be used with qualitative data.
i. Frequency table for 25 tomatoes growing in red ground cover
vs. no ground cover.
Red Ground Cover
Mode
Pink Tomatoes
Frequency Distribution
Red:
Pink:
Yellow:
Green:
Total
25 Plants
No Ground Cover
Red Tomatoes
0
12
8
5
Red:
Pink:
Yellow:
Green:
20
5
0
0
25 Plants
F. Overview of Data Analysis
Type of Information
Quantitative, Interval,
Qualitative
or Ratio Data
Nominal
Ordinal
What is the most typical or
Mean
Mode
Median
central value?
What is the variation or
Range
Frequency Distribution
spread?
Standard Deviation
G. Data Tables and Graphs
a. In addition to computing various descriptive statistics, you will need
to construct data tables and graphs that communicate the results.
b. You can use bar, histogram, or line graphs with quantitative data, but
you can only use bar graphs or histograms with qualitative data.
c. Each data table should have an appropriate title and graph which
explains it.