How many reversed cards should we expect? Many Tarot readers read reversed cards with slightly different meanings; we know that reversals have a lot of nuance in them, and don’t just mean “bad” things, but it can still be disconcerting to see seven or eight cards out of ten upside-down. Actually, people who work with reversed cards should be accustomed to seeing quite a few reversals in any spread, but it’s still hard to quantify whether any given number of reversals is unusual. It turns out that the binomial probability distribution can help us refine our expectations of how many reversed cards are usual in a typical spread.
While we know to expect “about” five reversed cards out of ten, the binomial probability distribution tells us that really anywhere from two to eight cards is not surprising.
The binomial probability distribution applies to situations where we have a number of independent events, each of which has two possible outcomes. In a Tarot spread, each card is an event, and its outcomes can be either upright or reversed. I’m going to assume that each card will be reversed about half the time, for a probability of 0.5. This assumes your method of reversing cards is truly random, but it will be a reasonable approximation for most methods.
The average number of reversals in a given spread will be the number of cards in the spread times the probability of a single card being reversed. For a ten card spread, the expected number of reversed cards is five. This intuitively makes sense; it’s when we get more or fewer that we start to wonder whether it happened by chance.
The number that helps us understand how much things differ from the expected is the standard deviation. For a probability distribution, the standard deviation is a measure of how wide the distribution is. This means it tells us how normal or weird a particular difference (deviation) from the expected value (standard) really is.
For a binomial probability distribution, we find the standard deviation by taking the expected value times the probability of the opposite outcome (which is also one half, or 0.5), and then taking the square root. For a spread of ten Tarot cards, the standard deviation works out to about 1.6.
Almost 70% of the time, when we deal ten cards, the number of reversed cards will be the average (five) plus or minus one standard deviation (1.6). Therefore most of the time, we should expect four to six reversed cards.
For 95% of readings, we’ll be within plus or minus two standard deviations, which means anywhere from two to eight cards reversed. This is important; it’s easy for us to look at six reversed cards and say that that’s close to five, so it’s normal, but when the reversals start creeping up towards eight, a significant majority of the reading, we can get nervous. Don’t!
Understanding that eight reversed cards is normal is an example of how math helps us refine our intuition. 95% of the time is a lot – this is nineteen times out of twenty. In only one out of twenty readings would you expect to get something outside of these bounds. How long does it take you to do twenty full Celtic Cross readings? Only once out of those twenty times would you see a reading with all reversed cards or all upright cards, or even a reading with just a single card upright or a single card reversed.
Of course, this kind of understanding is only a starting place for the real work of a Tarot reading. The specific meanings of the cards which are reversed, the patterns revealed in the layout, and most importantly the meanings that the client reads as applicable to her or his life, are much more important for the interpretation of a given Tarot reading, and they give each reading its unique qualities.
Still, the simple numerical understanding indicates that we should expect to work with what seems like a lot of reversed cards. Hopefully, knowing this means that the presence of these cards won’t necessarily make you disturbed or uncomfortable; they are a way for Tarot to give you a wider range of nuance and information, so engaging with them can lead to even more insight and understanding.