Results:
Mean Amount of Hh present
in cell
1 mg/mL
2 mg/mL
3 mg/mL
4 mg/mL
Mean # of cells killed by
apoptosis (S=10.62)
18
15
8
3
Mean # of adult stem cells
Mean # of cancer stem cells
510,560
501,760
343,856
215,880
1,440
10,240
90,144
100,120
*The amount of protein is measured by a protein assay. By measuring the absorbance of a protein you
can convert to get a concentration of protein in mg/mL.
Data Analysis
After the data collection, we need to analyze this data to determine if our results are significant and what they
mean for the treatment. To do this we are going to use a t-test and a linear regression. For your calculations,
p<0.05 is statistically different. Calculate the t-values by hand and use the calculator on the webpage for the
remaining calculations.
1. Is the difference between the mean amount of apoptosis in the hedgehog problem pathway before
treatment and the hedgehog problem pathway after treatment statistically significant? Show your work.
2. Is the difference between the mean number of cancer stem cells before treatment statistically different
from the mean number of cancer cells after treatment in the problem hedgehog pathway?
3.
Complete a linear regression between the mean amount of hedgehog present and the mean number of
cancer stem cells. Calculate the least squares line using the calculator given and then determine the r^2
value to determine if a linear regression is appropriate for the data. Explain why or why not.
Reflection Questions
Use your answers from the previous sections to complete the questions below. Be sure
to spend time thinking critically on these questions. They are designed to help you
reflect on the data collection and analysis.
1. Which sets were statistically different? What were your t-values and p-values?
2. What does a p-value of 0.049 mean?
3. What does a p-value of 0.061 mean? Why is this value not statistically significant?
4. Why do you think the number of cancer stem cells before and after treatment was
not statistically different? (HINT: Think about the procedure)
5. Why did you classify the relationship between amount of hedgehog and number of
cancer cells linear/not linear? How did your decision incorporate the r-squared value?
6. What were possible sources of error in this experiment?
7. If you were to repeat this experiment what would you do differently or what steps
would you add?