Variance and Statistical Testing Logic Quiz

What is the purpose of calculating percentiles?

To understand the area under the curve
To identify the rarest bean color
To determine the mean value
To find the percent of scores below a given score (correct)

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

Due to a biased selection process
Each individual has an equal chance of being selected (correct)
No relation exists between population distribution and sample distribution
Because of an unequal chance for each person to be picked

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

To calculate the mean value of the bean colors
To determine the color of the beans
To establish the odds of picking each bean color
To convert raw scores into a common scale for percentile calculation (correct)

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 (A) Signup and view all the answers

Which color bean has the highest percentile ranking?

Purple (A) Signup and view all the answers

What allows us to calculate percentiles in a distribution?

Knowing the area under the curve (B) Signup and view all the answers

What does within subjects variance measure?

How much people within a group differ among themselves (C) Signup and view all the answers

Which of the following is true about within group variance?

It reflects naturally occurring individual differences (C) Signup and view all the answers

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

Standard deviation (s.d.) (C) Signup and view all the answers

Between subjects variance refers to the variance between:

Sample means or groups (D) Signup and view all the answers

What does between subjects variance measure?

Difference between sample means of different groups (B) Signup and view all the answers

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

T = (z x 10) + 50 (B) Signup and view all the answers

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

Difference between any two people in a group (D) Signup and view all the answers

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

T score (A) Signup and view all the answers

What does a T score of 70 indicate?

It is 20 points above the mean (C) Signup and view all the answers

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

The score is exactly at the mean (B) Signup and view all the answers

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

Because T scores represent points above or below the mean (A) Signup and view all the answers

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 (B) Signup and view all the answers

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

Type I Error (C) Signup and view all the answers

When does a type II error occur?

The null hypothesis is true and not rejected (D) Signup and view all the answers

What does statistical significance indicate about group differences?

Differences are not due to chance (B) Signup and view all the answers

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

Type I Error (D) Signup and view all the answers

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

Sample size (B) Signup and view all the answers

Which statistic can quantify the practical significance of a finding?

$\eta$ statistic (C) Signup and view all the answers

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

To measure the relationship between two sets of observations (C) Signup and view all the answers

What does a z score help determine in psychometric tests?

The number of standard deviations a data point is from the mean (B) Signup and view all the answers

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 (A) Signup and view all the answers

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 (B) Signup and view all the answers

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 (C) Signup and view all the answers

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

Conducting multiple replications of the study (B) Signup and view all the answers