This exercise deals with both the metric system and the statistical
analysis of data taken from the human hand. You will learn how
to make bar graphs from the statistics you collect. The many people
in our world with two recessive genes for hitchhiker's
thumb are able to bend the distal joint of that digit. They can
bend their thumbs at an angle of 45 degrees or more. This is called
hyperextension of the thumb. People who carry either one allele
or two alleles for a thumb that is straight, or close to being
straight, are said to express the dominant gene.
- 1- thumb
- 1- metric ruler, mm and cm
- 2- graphs
- By using the picture below, measure your thumb in millimeters
from joint 2 to the tip of your finger. Do not include the measurement
of your fingernail.
- Record whether or not you have a hitchhiker's thumb
on the chart on the second page of this exercise.
- Record your measurement in millimeters in column A if you have
a hitchhiker's thumb and in column B if you have a straight
- Record the measurements of your classmates' thumbs on
the remaining part of this chart and determine average or mean
for A and an average or mean for B.
- Copy the graph picture provided to your graph paper, graph
the length of the thumb in mm on the Y axis, and record your class
data using a bar graph. Do only two columns in your graph, column
A and column B, hitchhiker's thumb and non-hitchhiker's
- Add the hitchhiker's thumb data from all of the classes
(chart 2) and find the average. Do the same with the straight
- Make a second bar graph with your two averages from #6 above.
of a Thumb
(You should use this picture to determine what to measure)
- Picture of a Hitchhiking Thumb
- CHART AND GRAPH
- Do you have hitchhiker's thumb? Circle your answer: YES NO
- If you have a hitchhiker's thumb, put your results in column A, and if not, put your results in column B. Add your fellow classmates to the remaining part of the chart.
- CHARTS FOR ALL OTHER BIOLOGY CLASSES:
- Record the data of other biology classes in the chart below.
- Put the hitchhiker's thumb trait on the left side of column A and the non hitchhiker's thumb trait on the right side of column A.
- For each additional biology class, record the data in columns B, C, D, and E just like you did in number 2 above.
KEY TO THE CAHRT BELOW:
- Column A = class 1
- Column B = class 2
- Column C = class 3
- Analysis Of Data
For a simple exercise (without formal statistical analysis), a
variation may be considered significant if you have at least a
20 percentage point or higher variation for hitchhiker's
thumb. To calculate this, you may use the following formula:
- ( 1- B/A) x 100 = % difference in mm
A = mm average x no. of people (hitchhiker's
B = mm average x no. of people (no hitchhiker's thumb)
For those who would like to consider statistically significant
differences use a t test which considers sample size. This
will allow you to calculate whether there is a significant
difference between your samples.
- Using the Formula
- Calculate the % difference for your class (graph) and record
your answer here.
- Calculate the % difference from the additional biology classes
(2nd graph) and record your answer here.
- Did the additional biology classes have a significant variation
for having a longer hitchhiker's thumb? (Circle: YES
NO.) If yes, how much?
- Did having more people randomly involved make a difference
in your results? (Circle YES NO.) How did you know this?
- Summarize what you have learned in this exercise about percent
differences in the average or mean of data. Write at least one
- Further Studies (Using
the data available)
- Determine the mean, medium, mode, range, and standard deviation.
- Demonstrate the Hardy-Weinberg Equilibrium.
- Randomly select 100 students on your campus and compare this data with the data taken in this exercise.