R practice in Statistics
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Clean the Readings
A missing reading is not zero; missingness mechanisms may still affect the resulting estimate.
na. Free room.
Count the Passes
A score exactly sixty passes; negative or lower scores do not.
numeric. Free room.
Keep the Gains
Break-even days are not gains and must be excluded.
indexing. Free room.
Tally the Ballots
Count before choosing a winner, and make tie handling explicit.
characters. Free room.
Fold the Receipts
Multiplication combines factors; a zero makes the total product zero.
functionals. Account access required.
Rank the Leaderboard
Return ranks in original observation order, not a sorted copy of the values.
mutate-arrange. Account access required.
Square the Batch
Mapping a function does not inherently remove iteration or guarantee faster execution.
apply. Account access required.
Summarize the Cohort
The result order is a then b regardless of which group has the larger mean.
grouping. Account access required.
Estimate the Odds
The quarter-circle area supplies the target; the realized simulation is not exactly pi. Preserve draw order for reproducibility.
simulation. Account access required.
Flag the Anomaly
A fence flags unusual values without proving measurement error; equality to a fence is not outside.
outliers. Account access required.
Read the Z-Table
The CDF is accumulated area, not density height at z.
continuous. Account access required.
Size Up the Spread
The coefficient of variation is unitless but depends on a meaningful measurement origin.
spread. Account access required.
Bracket the Mean
The interval concerns a population mean under independent-observation assumptions, not a range covering individual readings.
ci. Account access required.
Fit the Line
The fixed predictor spacing makes the slope half the difference between the final and first response.
leastsquares. Account access required.
Score the Fit
In-sample explained variation is not a future performance guarantee.
fit. Account access required.
Test the Claim
The independent-group test does not assume equal variances and does not establish causation.
ttest. Account access required.
Bootstrap the Error
The output estimates sampling variability under the empirical distribution, not the spread of raw observations.
sampling. Account access required.
Cross-Validate
Training rows must exclude the held-out fold. These folds are for independent observations, not time-series forecasting.
crossval. Account access required.
Forecast Next Quarter
Recover intercept=mean(current)-phi*mean(past), then add it to phi*last. Omitting it would use a different model from the one fitted.
forecast. Account access required.
Label the Model Fit
These classroom labels describe in-sample fit, not causal validity or held-out accuracy. Compare unrounded input.
report. Account access required.