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Quizme Development

Tuesday, Dec 25, 2018
R

Overall Structure

At the beginning following data structures are created (or read if these exist from an earlier session):

qtbl (question table): a data.table containing questions uniquely identified by id column

soltbl (solution table): a list containing answers again uniquely identified by id column

testlog (test log): a data.table that logs user responses each time they take the quiz. This contains columns on when the question was asked, how much time it took to answer and whether you knew the answer or not

ranktbl (ranking table): a data.table that ranks/orders the questions based on testlog data. This contains a status column based on which further control on ranking is established

slog (session log): a data.table containing info on each quiz session

User Functions

quizme(): This creates (or reads into memory) all the data structures described in the above section.

addq(): Updates the qtbl and soltbl objects. User input is collected using scan() function and stored in a character vector. First element (assumed as question) of this vector is added to qtbl while the rest (assumed as single or multiline answer) is added to soltbl. ranktbl is updated with this question using addToRankingTbl() and is added to a subset of new questions with year 2100 as due date to force it to the bottom of the list. This enables the user to add as many new questions as they want without getting overwhelmed with more test questions.

NOTE: Although addq() takes a character argument (tags) which will be added to qtbl column, I have found and employed a more concise way to add tags: start the question with a single letter followed by colon. For example, r: question can be used to add an R language question. It has the following advantages:

  1. It forces you to organize your tags in a more meaningful way. I think few tags are better than none or too many.
  2. Allows you to add the tags at the same time when adding a question with couple of extra keystrokes.

NOTE: Adding images as answers is also allowed. This is done by adding the text image to the answer and storing the image file as <id.png> in ./images directory.

ask(): Prompts the user with a question. The question belongs to a subset of ranktbl rows that are due today. Also, learning questions are given higher priority than the new questions. Within the subclass of learning and new questions, shuffling is done (using sample()) each time a question is asked. If there are no more questions that are due on a given day, user is prompted to add more questions if they wish to do so using a call to newMove().

tell(): Displays the answer to the last question asked. If the answer was in image format, that image is displayed in R's graphics window.

hit(): Response to the currently displayed question if the user answered the question correctly. testlog table is updated with this information. In addition, it also calls updatetime() which updates the ranktbl with the new due date/time for this question.

miss(): Response to the currently displayed question if the user did not answered the question correctly. testlog table is updated with this infomation.

bye(): To close the quiz session and update all the data tables. This is automatically called at the end of the quiz session. This can also be called in the middle of the quiz session as well. This makes it adaptive to the time available: if you just have 1 or 2 minutes, you can practice a few questions, and if you have more time, you can work to finish the quiz in one session.

changeq(): To edit the currently asked question. You may need this in situation where either simply there was a typo in the question/answer or you later learned a better answer that you want to replace your older answer with.

show_status(): This shows a summary of your learning including total number of questions in your quiz repository categorized by learning status (new, learning, learned, mastered). These are also shown by topic. Number of questions due today and tomorrow is also displayed.

week_ahead(): Displays the number of questions due for each day in the next seven days. This helps you plan your week in terms of scheduling more or less time for the quiz.

Backend Functions

addToRankingTbl(): This function adds the new question to ranktbl and then calls updateranktbl().

updateranktbl(): Reorders the questions in ranktbl by due date, then by status and finally by rank.

NOTE: ordering by rank was used originally to make it a function of the order in which the questions are added. Now that the questions are added randomly from a pool of new questions, rank column has become redundant. This will be removed in a later version.

updatetime(): This is where the spaced repetetion concept is implemented. This function calculates the interval as to when the correct question will be asked again. It uses the following logic to carry out the task:

For a new question and first correct response, time is not updated but rank is set to the highest. This is done to present the brand new question twice in the same session for better memorization.

NOTE: Here again, setting the rank is redundant. Earlier it was done to push this question to the bottom of the current list so it is not asked immediately again. Now that shuffling is carried out at the time of asking the question, this is not needed.

If a new question is answered correctly twice, 4 hours is added to its due column. This is done to push the question to the next session (assuming a session does not last longer than 4 hours).

If the new question is answered correctly again in the second session,

If a learning question is answered correctly, it calculates the interval based on two times:

a) last interval for this question using:

days_elapsed(): This function is called from updatetime() to calculate interval for learning questions. It calculates the number of days elapsed between the last two showings of a question.

b) how long did it take to answer the question using :

t_learning():

updaterank(): This function is called if the response to the question is miss(), i.e., the user failed to recall the correct answer. It does not update the interval, but only the rank, so it keeps the question in the same session until it is answered correctly.

mvPastdueToToday(): Called by quizme() to move all the questions that are past due to today. This is done to keep due times simple. There is no need to fret about overdue questions. It also helps in more realistic interval calculations. For example, if you answered a question that was due a week back and let's say the total interval to add for next showing is 3 days, this question will remain overdue even though you answered it correctly today, which does not make sense.

Controlling New Questions to Learn

Quizme allows you to add as many questions to the repository as you want because the number of questions you are learning actively is controlled independently. The following set of functions control how many new questions you want to learn. At the end of the quiz session (when all due questions are completed, 6 new questions are automatically added, and if those are completed as well, any number of additional questions can still be added (if available in the repository)).

newParked(): Helper function used in newMove(). Returns total number of new questions (only added to the repository but never practiced).

newActive(): Returns total number of new questions that are actively being learned.

newDelta() : Additional questions to be added to meet the target of 6 new questions.

newMove() : Main function that moves the requested number of questions from new repository to actively learning. It simply randomly selects the requested number of questions from new repository and changes their due date to today.

NOTE: After using the tool for a couple of months now, it appears that the logic to first add 6 questions automatically and then ask the user if they want to add additional questions is more confusing than it is useful. It would be simpler just to directly prompt the user to add the desired number of questions.

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