Statistical Programmer Interview Questions and Answers

Data step calculates row-wise means, while PROC MEANS computes column-wise means in SAS.

• Data step processes data row by row, allowing for custom calculations.

• Example: Using a data step to calculate the mean of multiple variables for each observation.

• PROC MEANS summarizes data column-wise, providing statistics like mean, median, and standard deviation.

• Example: PROC MEANS can quickly generate summary statistics for a dataset without needing to write complex code.

Clinical research is the study of drugs, devices, and treatments in humans to determine their safety and effectiveness.

• Clinical trials are conducted in phases to ensure safety and efficacy of the drug or treatment.

• Phase 1: Small group of healthy volunteers to determine safety and dosage.

• Phase 2: Larger group of patients to determine efficacy and side effects.

• Phase 3: Even larger group of patients to confirm efficacy and monitor adverse reactions.

• Phase 4: Post-marketing survei...read more

Baseline refers to the initial set of data used for comparison in clinical trials or studies.

• Baseline data is collected before any treatment or intervention is applied.

• It serves as a reference point to measure the effects of the treatment.

• For example, in a clinical trial for a new drug, baseline measurements of patients' health metrics (like blood pressure) are taken before administering the drug.

• Comparing post-treatment data to baseline helps assess the drug's effectiveness.

Mean in data step calculates mean within data step while proc means calculates mean for entire dataset.

• Mean in data step is calculated within the data step and only for the variables specified in the data step.

• Proc means calculates mean for the entire dataset or for the variables specified in the var statement.

• Data step mean can be used for conditional calculations while proc means is used for overall summary statistics.

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Different types of functions include linear, quadratic, exponential, trigonometric, and logarithmic functions.

• Linear functions have a constant rate of change, such as f(x) = 2x + 3.

• Quadratic functions have a squared term, such as f(x) = x^2 + 3x + 2.

• Exponential functions have a constant ratio between successive values, such as f(x) = 2^x.

• Trigonometric functions involve sine, cosine, and tangent, such as f(x) = sin(x).

• Logarithmic functions are the inverse of exponential functi...read more

Clinical study phases are stages of research that a new drug or treatment must go through before it can be approved for use.

• Phase 1: Small group of healthy volunteers to test safety and dosage

• Phase 2: Larger group to test effectiveness and side effects

• Phase 3: Even larger group to confirm effectiveness, monitor side effects, and compare to existing treatments

• Phase 4: Post-marketing studies to monitor long-term effects and safety