Z-Score Normal Distribution – Statistics PsycINFO

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Z-Score Normal Distribution, Probability And Correlation – STATS Exam

The key terms in these Statistics chapters include z-score, Normal Distribution, Probability, Population, Mental Process And Behavior, Distribution, Random Sample, Variable, Pearson Correlations, Variance, Mean, Population Correlation – Statistics PsycINFO Exam


What is the probability of randomly selecting a z-score greater than z = -0.75 from a normal distribution?

p = 0.7734 (body)


A normal distribution has µ = 20 and σ = 4. Which is the probability of randomly selecting a score greater than X = 25 from this distribution?

p = 0.1056


A researcher tests their new treatment for sleep disorder among an individual that has a sleep disorder. The researcher knows that individuals diagnosed with sleep disorder tend to have sleep quality scores that form a normal distribution with µ = 40 and σ = 6. The researcher finds that this individual has a sleep quality score of X = 53 following treatment. Which is the probability that a score this large or larger would be obtained if the new treatment had no effect?

p = 0.0150 (tail)


A normal distribution has a mean of µ = 40 with σ = 10. If a vertical line is drawn through the distribution at X = 34, which proportion of the scores are on the left side of the line?

0.2743


What is the probability of randomly selecting a z-score greater than z = -0.75 from a normal distribution?

p = 0.7734 (body)


A normal distribution has µ = 20 and σ = 4. Which is the probability of randomly selecting a score greater than X = 25 from this distribution?

p = 0.1056


Suppose we have a set of sample data and we compute the standard deviation to be 5.50. This means that the numbers in the sample generally deviate:

5.50 units from the mean


Rasheed and Xavier are examining the GRE math scores of the 25 graduate students in their statistics class to see the variability. They found the variance to be 1296. What is the standard deviation?

36


If the variance for a sample is computed and it is found to be rather large, the numbers in the sample are:

Widely spread out around the mean.


z score formula

(X-mean)/standard deviation


A tenet of the scientific method is that _____ allow researchers to examine mental processes and behavior in an empirical, scientific manner.

Operational definitions


The mathematical expression of Σ X – 2 differs from the mathematical expression of Σ( X – 2) in each of the following ways except for which?

Squaring takes place in one equation but not the other.


If you could somehow magically know the mean monthly cost of ramen noodles for all college students in the entire world, that mean would be an example of a _____.

Parameter


What is the probability of randomly selecting a z-score greater than z = -0.75 from a normal distribution?

p = 0.7734 (body)


A normal distribution has µ = 20 and σ = 4. Which is the probability of randomly selecting a score greater than X = 25 from this distribution?

p = 0.1056


A researcher tests their new treatment for sleep disorder among an individual that has a sleep disorder. The researcher knows that individuals diagnosed with sleep disorder tend to have sleep quality scores that form a normal distribution with µ = 40 and σ = 6. The researcher finds that this individual has a sleep quality score of X = 53 following treatment. Which is the probability that a score this large or larger would be obtained if the new treatment had no effect?

p = 0.0150 (tail)


A normal distribution has a mean of µ = 40 with σ = 10. If a vertical line is drawn through the distribution at X = 34, which proportion of the scores are on the left side of the line?

0.2743


What is the probability of randomly selecting a z-score greater than z = -0.75 from a normal distribution?

p = 0.7734 (body)


If it is impossible to divide the existing categories of a variable, then it is an example of a(n) _____ variable.

Discrete

One limitation of the empirical method is that ____.

The process can be time consuming and often risky


A scientist runs a study in which a bunch of college students solve word search puzzles after drinking different kinds of beer. In the study, the students are referred to as ____.

Participants


The most complete coverage of existing journals is provided by full-text databases.

False


You searched PsycINFO and got several hundred articles. The most efficient thing to do next is ____.

Scan through the titles to see which ones seem most suited to your interests


Suppose the correlation between height and weight for adults is r = +0.40. Which proportion (or percent) of the variability in weight can be explained by its relationship with height?

16%


For which of the following Pearson correlations would the data points be clustered most closely around a straight line?

r = – 0.70

Under which circumstances is the phi-coefficient used?

When both variables are dichotomous


For a two-tailed hypothesis test evaluating a Pearson correlation, what is stated by the null hypothesis?

The population correlation is zero.


Which of the following is not an aspect involved in computing the sum of products ( SP) of deviations?

Subtracting the total sum of squares collapsed across all scores


A linear regression equation has b = 3 and a = – 6. What is the predicted value of Y for X = 4?

Ŷ = 6


Which of the following actions would have the effect of either changing the size or direction (sign) of a Pearson r value pertaining to a set of X and Y scores?

Multiplying each X and Y score by a negative constant value


A population is normally distributed with µ = 145 and σ = 20. Which is the percentile rank for X = 171?

90.32% (body)


Formula to find x (with z score)

Mean + (z score)(standard deviation)


Transforming a set of scores into a standardized distribution of z-scores consists of graphically _____ the scores.

Relabeling


What is the variance for the following population of scores? Scores: 2, 5, 6, 3

2.50


On an exam with a mean of µ = 70, a person scores X = 60. Which of the following values for the standard deviation would position this person highest within the class?

σ = 15


The relationship between a statistic and a sample is the same as the relationship between _____.

A parameter and a population.


___________ are cues to participants about how they’re expected to behave in a study

Demand characteristics


Dr. Harmony is a social psychologist. In one study she measures relationship satisfaction in couples by observing non-verbal behavior (e.g., smiling, mimicking partner actions). For that study, non-verbal behavior is an example of a(n) _____.

Operational definition


Which of the following is necessary in order to obtain a random sample?

Ensure that each person in the population has an equal chance of being selected for the sample


Which section of a research article is most likely to provide suggestions for additional research?

Discussion


What is the probability of randomly selecting a z-score greater than z = -0.75 from a normal distribution?

p = 0.7734 (body)


A normal distribution has µ = 20 and σ = 4. Which is the probability of randomly selecting a score greater than X = 25 from this distribution?

p = 0.1056


A researcher tests their new treatment for sleep disorder among an individual that has a sleep disorder. The researcher knows that individuals diagnosed with sleep disorder tend to have sleep quality scores that form a normal distribution with µ = 40 and σ = 6. The researcher finds that this individual has a sleep quality score of X = 53 following treatment. Which is the probability that a score this large or larger would be obtained if the new treatment had no effect?

p = 0.0150 (tail)


A normal distribution has a mean of µ = 40 with σ = 10. If a vertical line is drawn through the distribution at X = 34, which proportion of the scores are on the left side of the line?

0.2743


What is the probability of randomly selecting a z-score greater than z = -0.75 from a normal distribution?

p = 0.7734 (body)


A linear regression equation has b = 3 and a = – 6. What is the predicted value of Y for X = 4?

Ŷ = 6


Which of the following actions would have the effect of either changing the size or direction (sign) of a Pearson r value pertaining to a set of X and Y scores?

Multiplying each X and Y score by a negative constant value


A population is normally distributed with µ = 145 and σ = 20. Which is the percentile rank for X = 171?

90.32% (body)


Formula to find x (with z score)

Mean + (z score)(standard deviation)


Transforming a set of scores into a standardized distribution of z-scores consists of graphically _____ the scores.

Relabeling


What is the variance for the following population of scores? Scores: 2, 5, 6, 3

2.50


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