## 30 Questions

What is the purpose of calculating percentiles?

To find the percent of scores below a given score

Why is random sampling from a normally distributed population likely to result in a normally distributed sample?

Each individual has an equal chance of being selected

What is the significance of z-scores in calculating percentiles?

To convert raw scores into a common scale for percentile calculation

How does the rarity of a bean color change as we move further from the mean?

The rarity increases as we move further from the mean

Which color bean has the highest percentile ranking?

Purple

What allows us to calculate percentiles in a distribution?

Knowing the area under the curve

What does within subjects variance measure?

How much people within a group differ among themselves

Which of the following is true about within group variance?

It reflects naturally occurring individual differences

What is the most commonly reported measure of within group variance?

Standard deviation (s.d.)

Between subjects variance refers to the variance between:

Sample means or groups

What does between subjects variance measure?

Difference between sample means of different groups

What is the formula to convert a z score to a t score?

T = (z x 10) + 50

In statistical terms, what does between subjects variance NOT refer to?

Difference between any two people in a group

Which score has a mean of 50 and a standard deviation of 10?

T score

What does a T score of 70 indicate?

It is 20 points above the mean

In z scores, what does a mean of 0 indicate?

The score is exactly at the mean

Why are T scores easier to explain compared to z scores?

Because T scores represent points above or below the mean

How can we use multiple z scores on psychologically meaningful measures from the same person?

By looking at how each z score deviates from its respective mean

What type of error occurs when the null hypothesis is actually true but is rejected?

Type I Error

When does a type II error occur?

The null hypothesis is true and not rejected

What does statistical significance indicate about group differences?

Differences are not due to chance

Which error occurs when a statistically significant finding has little practical importance?

Type I Error

What is the main reason for discrepancies between statistical and practical significance?

Sample size

Which statistic can quantify the practical significance of a finding?

$\eta$ statistic

What is the Pearson product-moment correlation coefficient 'r' commonly used for?

To measure the relationship between two sets of observations

What does a z score help determine in psychometric tests?

The number of standard deviations a data point is from the mean

Why can inferential statistics never prove that observed differences are not due to chance?

Because statistical tests estimate the odds that results are not due to chance

What is one of the key limitations mentioned regarding statistical tests like the t-test and correlation coefficient?

They can't fully eliminate the possibility of chance influencing results

What characteristic is common between naturally occurring phenomena like IQ and heights, and statistical test results like 'r' correlation coefficient?

They follow a bell-shaped curve distribution

What factor contributes to providing stronger support for the validity of a study?

Conducting multiple replications of the study

Test your understanding of variance and statistical testing logic. Explore the concepts of within group variance, between group variance, and co-variance to estimate significance levels.

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