Assignment: Kaplan-Meier Curve
The Kaplan-Meier curve is a way to evaluate longitudinal data and estimate conditional survival rates through the illustration of a series of conditional probabilities.
For this Assignment, you use the Kaplan-Meier method to evaluate time-to-event data collected through a longitudinal study described in the Week 8 Dataset (SPSS document). You also create a survival curve and estimate survival distributions.
The Assignment
Using Week 8 Dataset (SPSS document) from the Learning Resources area, answer the following:
1. Data (20 Points)
1. Create a variable for Time-to-event by subtracting the start time (variable = start) from the stop time (variable = stop). Label the new variable “Time”. (10 Points)
2. Produce the appropriate descriptive statistics, numerical and graphical, for the following variables: (10 Points)
o Event
o Interval
o Tx
o Num
o Size
o Time
2. Kaplan-Meier Survival Analysis (Without factor or Strata) (30 Points)
0. Run a Kaplan-Meier analysis in SPSS, using Time as the Time variable and Event as the Status variable (Be sure to define the event). Do not add a factor or strata at this time.
1. Produce a Survival Table (you do not need to submit this) (10 Points)
2. Produce a plot of the survival function (10 Points)
3. What is the mean survival time (include confidence intervals)? What is the median survival time (include confidence intervals)? Why do you think they are so different from each other? (10 Points)
3. Kaplan-Meier Survival Analysis (With Factor) (30 Points)
0. Run a Kaplan-Meier analysis in SPSS, using Time as the Time variable and Event as the Status variable (Be sure to define the event). Add Tx as the factor.
1. Test the difference between Tx groups (Compare Factor) using Log-Rank, Breslow, and Tarone-Ware (10 Points)
2. Produce a plot of the survival function (10 Points)
3. Describe what the Overall Comparisons mean in terms of treatment groups and survival times. (10 Points)
4. Kaplan-Meier Survival Analysis (With Strata) (20 Points)
? Run a Kaplan-Meier analysis in SPSS, using Time as the Time variable and Event as the Status variable (Be sure to define the event). Add Interval as the Strata variable.
? Produce a plot of the survival function for each strata. (10 Points)
? Why would you want to produce Kaplan-Meier Survival Curves after stratifying for a variable? (10 Points)
See reading material below
Daniel, WW & Cross, CL. (2013). Biostatistics: A Foundation for Analysis in the Health Sciences. Hoboken, NJ: Wiley.
• Chapter 14: Survival Analysis (pp. 750-767)
Telke, S. E., & Eberly, L. E. (2011). Statistical hypothesis testing: Associating patient characteristics with an incident condition: Kaplan-Meier curves, hazard ratios, and Cox proportional hazards regression. Journal of Wound, Ostomy, and Continence Nursing, 38(6), 621–626.
Note: Retrieved from Walden Library databases.
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