Exam prep · Free college course
A complete introductory statistics course, built from the 13 chapters of OpenStax Introductory Statistics 2e. It starts with data, sampling and experimental design, then descriptive statistics: percentiles, quartiles, box plots, the mean and median, and spread. Probability follows, with independent and mutually exclusive events, contingency tables and tree diagrams, and then the discrete and continuous distributions: binomial, geometric, hypergeometric, Poisson, uniform and exponential. The normal distribution and the Central Limit Theorem lead into inference: confidence intervals for means and proportions, hypothesis tests with one and two samples, Type I and Type II errors, chi-square tests, linear regression and correlation, and one-way ANOVA with the F distribution. Every calculation (standard deviation, z-scores, probabilities, standard errors, interval bounds, test statistics, chi-square, the regression line, the F ratio) is a typed card whose answer was recomputed by script, and no card makes you read a z, t, chi-square or F table or use a calculator: the value you need is in the question. Cards are text only, so every graph is described in words or as a small data table.
Copied straight from the course. In the app, each wrong option also gets its own explanation.
Card 1On Test A (mean 70, standard deviation 10) you scored 85. On Test B (mean 25, standard deviation 4) you scored 33. Which result is stronger relative to its group?
Test B, because its z-score of 2.0 is larger than 1.5. Test A: z = (85 - 70)/10 = 1.5. Test B: z = (33 - 25)/4 = 2.0. Test B is further above its own mean.
Card 2Which statement is a correct reading of a 95% confidence level?
About 95% of intervals built this way capture the parameter. The level is a statement about how often the procedure succeeds across repeated random samples.
Card 3With alpha = 0.01 and a p-value of 0.025, what is the decision?
Do not reject H0, since 0.025 exceeds 0.01. The p-value 0.025 is not less than alpha = 0.01, so the evidence is not strong enough to reject H0.
Yes. Create a free Encodr account and all 13 units and 1,250 cards are yours to study, with spaced repetition scheduling your reviews.
OpenStax Introductory Statistics 2e (all 13 chapters, CC BY-NC-SA) and standard introductory definitions. The cards are rewritten, not copied.
Sampling and data, descriptive statistics, probability, discrete and continuous distributions, the normal distribution, the Central Limit Theorem, confidence intervals, one- and two-sample hypothesis tests, chi-square tests, linear regression and correlation, and one-way ANOVA.
Yes. Standard deviation, z-scores, probabilities, standard errors, confidence intervals, test statistics, chi-square, the regression line and the F ratio are typed practice cards, and every answer was recomputed by script.
No. Questions that need a table value give it to you, so the cards test which value to use and what the result means. Only the standard z values for common confidence levels are expected from memory.
No. Cards are text only, so histograms, box plots and scatter plots are described in words or as a small data table.