Log in 😊 8 years agoPosted 8 years ago. Direct link to 😊's post “how do I calculate the pr...” how do I calculate the probability of a z-score? • (20 votes) Piquan 8 years agoPosted 8 years ago. Direct link to Piquan's post “That's a great question! ...” That's a great question! Fortunately, the next set of lessons, at https://www.khanacademy.org/math/statistics-probability/modeling-distributions-of-data/normal-distributions-library/v/ck12-org-normal-distribution-problems-qualitative-sense-of-normal-distributions , discuss exactly that. It's great that you're thinking ahead! (27 votes) Nick Leshuk 8 years agoPosted 8 years ago. Direct link to Nick Leshuk's post “how do you calculate the ...” how do you calculate the mean when you are only given the z-scores? • (5 votes) RacheLee 8 years agoPosted 8 years ago. Direct link to RacheLee's post “To calculate the mean, yo...” To calculate the mean, you need to know z-scores, the data, and the standard deviation. (14 votes) Tou 6 years agoPosted 6 years ago. Direct link to Tou's post “how do you calculate this...” how do you calculate this: µ=10 and σ =1, P(X>10) • (6 votes) Shaghayegh 4 years agoPosted 4 years ago. Direct link to Shaghayegh's post “Is it necessary to assume...” Is it necessary to assume the distribution is normal? • (3 votes) loumast17 4 years agoPosted 4 years ago. Direct link to loumast17's post “to use z scores. If not,...” to use z scores. If not, or you do not know the population standard deviation you would use a different kind of score called the t score For z scoreyou need both the population standard deviation and for the sample to be greater than 30. There are other aspects in statistics where having a normal distribution is necessary. (7 votes) 1315031658 7 years agoPosted 7 years ago. Direct link to 1315031658's post “How do you find the data ...” How do you find the data when you have the mean, the z-score, and the standard deviation? • (2 votes) Ian Pulizzotto 7 years agoPosted 7 years ago. Direct link to Ian Pulizzotto's post “Let x represent the data ...” Let x represent the data value, mu represent the mean, sigma represent the standard deviation, and z represent the z-score. So the data value equals the z-score times the standard deviation, plus the mean. Have a blessed, wonderful day! (7 votes) sebastian grez 8 years agoPosted 8 years ago. Direct link to sebastian grez's post “what happens when you get...” what happens when you get the number of X-U/standar desviation ahd you get a number above 3, that number will not be in the tabla of Z • (4 votes) psthmn 8 years agoPosted 8 years ago. Direct link to psthmn's post “You could try to find a m...” You could try to find a more extensive Z table, for example here: http://www.intmath.com/counting-probability/z-table.php But at a certain point the difference in probality at changing z values gets vanishingly small, so it doesn't really matter what the actual value at that point is. If you are faced with this situation, in most cases P > P(Z=3) is a useful and sufficient answer. (1 vote) Bryan 4 years agoPosted 4 years ago. Direct link to Bryan's post “Are z-scores only applica...” Are z-scores only applicable for normal distributions? You could describe how many standard deviations far a data point is from the mean for any distribution right? But is the term z-score only for normal dists? • (3 votes) Rebecca 4 years agoPosted 4 years ago. Direct link to Rebecca's post “The z-score could be appl...” The z-score could be applied to any standard distribution or data set. It definition only depends on the (arithmetic) mean and standard deviation, and no other qualitative properties of the nature of the data set. (2 votes) Samael Pena 5 years agoPosted 5 years ago. Direct link to Samael Pena's post “What if I don't have the ...” What if I don't have the score but only the Z score. How can I calculate what the score is • (3 votes) muhammad fajar rizqi 7 years agoPosted 7 years ago. Direct link to muhammad fajar rizqi's post “Hello Everybody, I want t...” Hello Everybody, I want to ask, how to calculate that has z-score is more than 3 or -3? because sometimes i calculate the z-score and can't get the result because it's out of range from the z-table. Thank you • (3 votes) Rosivette Andrade 5 years agoPosted 5 years ago. Direct link to Rosivette Andrade's post “Would anyone mind explain...” Would anyone mind explaining this ? A. about 2 • (2 votes)Want to join the conversation?
z-score=(data-mean)/standard deviation
data-mean=(z-score)(standard deviation)
mean=(data)-(z-score)(standard deviation)
Since the z-score is the number of standard deviations above the mean, z = (x - mu)/sigma.
Solving for the data value, x, gives the formula x = z*sigma + mu.
For a normal distribution of 1000 cases, how many cases will be farther away from the mean than + 3 standard deviations?
B. at least 500
C. it is impossible to estimate
D. 327
FAQs
How to calculate Z-scores (formula review) (article) | Khan Academy? ›
Let x represent the data value, mu represent the mean, sigma represent the standard deviation, and z represent the z-score. Since the z-score is the number of standard deviations above the mean, z = (x - mu)/sigma. Solving for the data value, x, gives the formula x = z*sigma + mu.
How to interpret az score? ›If a Z-score is equal to 0, that means that the score is equal to the mean. If the score is greater than 0 or a positive value, then that score is higher than the mean. And when a z-score results in a value less than 0 or a negative value, that means that the score is below the mean.
How to calculate z-score calculator? ›- Calculate the mean as (∑x) / n .
- Calculate the standard deviation using the easy-to-type formula (∑(x²) - (∑x)²/n) / n . The divisor is modified to n - 1 for sample data.
- Calculate the z-score using the formula z = (x - mean) / standard deviation .
To calculate a z-score, we simply subtract the mean from a raw score and then divide by the standard deviation. (On exam questions, the mean and standard deviation may be provided, or you may need to calculate them, so make sure you know how to do that!)
What is the formula for calculating the z-score? ›Z Score = (x − x̅ )/σ
Where, x = Standardized random variable. x̅ = Mean. σ = Standard deviation.
Z-score is a result of standardizing an individual data point. Simply put, a z-score gives us an idea of how far the data point is from the mean measured in terms of standard deviation(σ). For instance, a z-score of 2.5 indicates that the value is between 2 to 3 standard deviations from the mean and is not so common.
How to find z-score without table? ›To calculate the standard error of the mean, you can use the following formula:Z = (x - μ) / (σ / √n)Where: x is the data point you choose. μ is the mean. σ is the standard deviation.
What is the original formula for the z-score? ›The formula for Altman Z-Score is 1.2*(working capital / total assets) + 1.4*(retained earnings / total assets) + 3.3*(earnings before interest and tax / total assets) + 0.6*(market value of equity / total liabilities) + 1.0*(sales / total assets).
What is the z-score for a 95 confidence interval? ›The Z value for 95% confidence is Z=1.96.
How is the z-score table calculated? ›Z-Score Formula
It is a way to compare the results from a test to a “normal” population. If X is a random variable from a normal distribution with mean (μ) and standard deviation (σ), its Z-score may be calculated by subtracting mean from X and dividing the whole by standard deviation.
How to find z-score with mean and percentile? ›
1 Answer. Z = (x - mean)/standard deviation. Assuming that the underlying distribution is normal, we can construct a formula to calculate z-score from given percentile T%.
How do you find the z-score of a probability? ›The Z-score formula is z = x − μ σ .
How to find z-score in Excel? ›The formula for computing a z-score is =(DataValue-Mean)/StDev. For example, to compute a z- score for the first value in our data set, we use the formula =(A2-$D$2)/$E$2 as Figure 1 illustrates. Notice the dollar signs $ in the formula. These dollar signs are what are known as absolute markers.
What is the formula for z-score for a child? ›Based on body mass Index (BMI)
Z-score and percentile equivalence: 3SD=0.1%; 2SD=2.3%; 1SD=15.9%; +1SD=84.1%; +2SD=97.7%; +3SD=99.9%.
The formula for determining sample size to ensure that the test has a specified power is given below: where α is the selected level of significance and Z 1-α /2 is the value from the standard normal distribution holding 1- α/2 below it. For example, if α=0.05, then 1- α/2 = 0.975 and Z=1.960.
How do you interpret the results of the z test? ›A Z-score of 2.5 means your observed value is 2.5 standard deviations from the mean and so on. The closer your Z-score is to zero, the closer your value is to the mean. The further away your Z-score is from zero, the further away your value is from the mean.
What does AZ score of 0.5 mean? ›Z-Scores and the 68-95-99.7 Rule
From the z-table we can determine that for a z-score of 0 the number is 0.5. This indicates that 50% of the data values lie below the mean and therefore 50% of the data values lie above the mean.
- Positive z-score: If a z-score is positive, it indicates that the data point is above the mean. ...
- Negative z-score: If a z-score is negative, it indicates that the data point is below the mean. ...
- Zero z-score: A z-score of zero indicates that the data point is equal to the mean.
Z-score equal to 0 means an average value, while a z-score of +1 means the value is one SD above the mean value of the population. Z-score charts (also known as centile growth charts) are used in paediatric growth follow-up and to compare anthropometrical variables to detect the presence of malnutrition or disease [3].