(2) Core Data Structures and Summaries – Practical
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Step 1 / 6
Step 1: Create vectors and factor
Build baseline objects.
heights <- c(10.2,11.1,10.8,11.4,10.9,12.0,12.5,12.2,12.8,12.3)
treatment <- factor(rep(c("Control","Treatment"), each = 5))
Step 2: Build data frame
Combine columns into a tidy table.
df <- data.frame( plant_id = 101:110, treatment = treatment, height_cm = heights, leaf_count = c(6,7,6,8,7,8,9,8,9,10) )
Step 3: Inspect structure
Verify data types before summaries.
str(df) summary(df)
Step 4: Compute grouped summaries
Calculate means by treatment group.
aggregate(height_cm ~ treatment, data = df, FUN = mean) aggregate(leaf_count ~ treatment, data = df, FUN = mean)
Step 5: Check category counts
Validate levels and sample sizes.
table(df$treatment) unique(df$treatment)
Step 6: Interpret results
Write one sentence interpretation for each table.
# Interpretation # Treatment mean height is ... # Sample size balance is ...
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