TR

What are these numbers telling you?

Ki-kare opens every topic of an introductory statistics course with one question: what is this for? Then it lets you calculate with your own data and shows the solution step by step, just as on an exam paper.

Start with the topicsGo straight to calculating

Mean
523.3
Median
516
Standard deviation
51.1
Coefficient of variation
9.8%
  • There is a small gap between the mean (523.25) and the median (516): the distribution is slightly right-skewed.
  • The standard deviation is 51.08 kg/da. Roughly speaking, most values lie between 472.17 and 574.33 kg/da.

Course chapters

  1. Why does statistics exist?

    To understand what the numbers in front of us represent and how sure we can be about them.

    Population and sample, Parameter and statistic, Data types and scales, Count or ratio?

  2. Organizing raw data

    To see at a glance which values occur how often, instead of staring at hundreds of numbers one by one.

    Simple frequency table, Grouped frequency table, Histogram, Frequency polygon

  3. Summarizing data with a few numbers

    To describe the centre of a data set and how spread out it is with two or three numbers.

    Means, Median and mode, Standard deviation, Quartiles, Coefficient of variation

  4. Taking chance into account

    To express in numbers how likely an event is.

    Multiplication and addition rules, Permutations, Combinations

  5. The shape of data

    To recognise which theoretical distribution our data resembles and compute probabilities from it.

    Binomial, Poisson, Normal distribution and Z score, t, χ² and F, Skewness and kurtosis

  6. Is the difference real?Extra topic

    To decide whether an observed difference is real or due to chance, knowing how likely you are to be wrong.

    Stating hypotheses, p-value, t tests, Confidence interval, Chi-square tests

  7. Comparing several treatmentsExtra topic

    To compare three or more fertilizer rates, varieties or practices in a single test and find out which ones differ.

    Analysis of variance (ANOVA), Completely randomized design, Randomized complete blocks, LSD and letter display, Coefficient of variation of a trial

  8. The relationship between two measurementsExtra topic

    To see whether two traits change together and to predict one from the other.

    Correlation coefficient, Simple linear regression, Coefficient of determination (R²)

  9. Testing two factors togetherExtra topic

    To study two factors such as variety and fertilizer in the same trial and see whether the effect of one depends on the other.

    Factorial experiments, Interaction, Split-plot designs, Two error terms

A solution, not just an answer

Every calculation starts from the formula and shows the intermediate steps with your numbers. You can check your own work line by line.

The methods from the course

Standard deviation with n − 1, quartiles at position (n + 1)/4, class width from the estimated range. Where methods differ, the page says which one it used.

Your data stays with you

All calculations run in your browser. Numbers you paste from Excel are never sent to a server unless you choose to save them.