Module 4 Stats Questions & Answers (RATED A+)

Module 4 Stats Questions & Answers
(RATED A+)
What term refers to a frequency distribution that follows a bell-shaped, symmetrical,
and unimodal curve? - ANSWERnormal distribution

In a normal distribution, the mean is located where? - ANSWERin the middle of the
curve

T/F For a normal curve, the median, mean, and mode are typically equal

T/F The area below the curve is 120%. - ANSWERTrue

False. 100% or 1.00

T/F The greater the standard deviation, the less spread out the normal curve. -
ANSWERFALSE

However, the rule only works when values are exactly 1, 2, or 3 standard deviations
away from the mean. In order to apply the concept of proportions to other standard
deviation values, such as σ = ± 1.4 or σ = ± 2.3, scores or values in the dataset must
be standardized.

an exact value that is observed - ANSWERraw score

indicates exactly how many standard deviations a raw score is above or below the
mean. - ANSWERstandard score


The greater the standard deviation, the more spread out the normal curve. The
smaller the standard deviation, the narrower the normal curve.

A normal distribution can be defined by its ___ and ______. - ANSWERmean and
standard deviation

the ___-___-___ rule

con? - ANSWER68-95-99.7
describes the exact location of a raw score within the whole distribution when
compared to the mean. It converts each raw score X into a signed, numerical value.
also known as standard scores - ANSWERz-score

What does a +z-score mean?

what does a -z-score mean? - ANSWERthe value from the dataset lies above the
mean

, the value from the dataset lies below the mean

Coverting raw scores to z-scores - ANSWERz= (raw score- mean)/ standard
deviation

Converting z-scores to raw scores - ANSWERraw score= mean + z * standard
deviation

Comparing Values using z-Scores and Raw Scores

When comparing z-scores from the same population or sample, it may be more
meaningful to convert the z-score back to a raw score. For example, compare the
performances of the following students on the physiology exam (μ = 87 , σ = 4 )
given the -scores listed below for Josef, Marco, and Brooklyn.
Josef: z=-1.75
Marco: z=-2.50
Brooklyn: z=1.25 - ANSWERConvert each z-score to a raw score. Then compare the
raw scores.
Josef: X=87 - 1.75(4) = 80
Marco: X= 87 - 2.50(4) = 77
Brooklyn: X= 87 + 1.25(4) = 92

z-Scores for Sample Means from a Population - ANSWER(sample mean-population
mean)/ population mean/ sqrt(sample size)

Consider the example of the exam scores from Figure 4.3 ( μ = 75 , σ = 5 ). Suppose
the teacher would like to know the proportion of scores on the exam that are below
65. - ANSWER1. transform raw score to a z-score
2 use normal table to find the p-value for z score

The proportion of scores below the z= -2.00 is 0.02275 or 2.275%. Therefore, a test
score below 65 is unusual since less than 2.275% of the scores fall below it.

a range of values that is likely to contain the true population mean. -
ANSWERconfidence interval

What states that the distribution containing all sample means will approach the
population mean. This implies that the population mean will be close to the sample
mean. - ANSWERThe Central Limit Theorem

95% confidence interval - ANSWERhe 95% confidence interval, for example, means
that 95% of the experiments with the given treatment will contain the true population
mean. Consequently, 5% (or 1 in 20) of the experiments will not contain the true
population mean. A 95% confidence interval implies that the researcher is 95%
confident that the population mean lies in the interval that is centered around the
sample mean.

margin of error - ANSWERz crit *(population standard deviation/ sqrt (sample size)