1. Which branch of statistics (“inferential” or “descriptive”) helps researchers to summarize data so they can be easily comprehended?

Descriptive data is used to summarize data so it can be easily comprehended.

1. Which branch of statistics help researchers to draw inferences about the effects of sampling            

   errors on their results?

1. If a researcher tests a random sample instead of all members of a population, is it likely that the sample results will be the same as the results the researcher would have obtained by testing the population?

No, because a sample is not a guarantee of similar results of population.  Even with inferential statistics, samples are not a way to get the “same” result of the population.

1. Is a margin of error a “descriptive” or an “inferential” statistic?

Margin of error is inferential statistics.

1. Are significance tests associated with “descriptive” or “inferential” statistics?

1. By studying populations, do researchers obtain “statistics” or “parameters”?

By studying populations, researchers obtain parameters.

1. By studying samples, do researchers obtain “statistics” or “parameters”?

By studying samples, researches obtain statistics.

1. The most frequently occurring score is mode.

1. Mean

1. Median

1. Mean is the value around which the deviation sum is zero

1. Add up the scores and divide by the number of scores

1. If it is highly skewed the mean should be used because it is not affected by extreme scores

1. Which average is usually reported when the standard deviation is reported?

The standard deviation is used to describe the variability from the mean.

1. What is meant by the term variability?

The term variability discusses the amount by which participants in an experiment differ or vary from each other.  Variability is the difference between the scores.

1. Is it possible for two groups to have the same mean but different standard deviations?

Yes, depending on the scores or numeric value, the averages can be the same but the variation between those scores can be different, therefore, the standard deviations can vary.

1. If all individuals in a group have the same score, what is the standard deviation for the scores?

If all scores are the same, the standard deviation would equal zero (0).

1. What percentage of the participants lies within one standard-deviation units of mean (i.e., on both sides of the mean) in a normal distribution?

1. The middle 68% of the participants in a normal distribution have scores between what two values if the mean equals 100 and the standard deviation equals 15?

With a mean of 100 and the standard deviation 15, the values of the middle 68% would be 85 and 115.

1. If the mean of a normal distribution equals 50 and the standard deviation equals 5, what percentage of the participants have scores between 45 and 50?

34% of the participants in a normal distribution would have scores between 45 and 50.

1. Does the 68% rule strictly apply if a distribution is not normal?

No, it does not.  The less normal I it is, the less accurate the 68% rule is.

1. If a researcher asks participants to name the country in which they were born, the researcher is using which scale of measurement?

The researcher is using a nominal scale of measurement.

1. Which two scales of measurement have equal distances among the scores they yield?

Interval and ration have equal distances.

1. If a researcher assigns a teacher to rank students according to their oral language skills, the researcher is using which scale of measurement?

Ordinal scale would rank their oral language skills.

1. Which scale of measurement has an absolute zero?

Ratio scale has an absolute zero.

1. Which scale of measurement is at the lowest level?

Nominal scale is at the lowest level.

1. Objective, multiple choice achievement tests are usually assumed to measure at what level?

These types of tests measure at an interval level.

1. If a researcher measures in such a way that he or she finds out which participant is the most honest, which is the next most honest, and so on (without measuring to determine how much honesty each one has), the researcher is measuring with what scale of measurement?

Ordinal scale will measure honesty without measuring the value of honesty.

1. The number of minutes of overtime work that employees perform is an example of which scale of measurement?

Ratio intervals measure overtime.

1. Weight measured in pounds is an example of which scale of measurement?

Weight is a ratio measurement.

1. If the median for a group of participants is 25.00, what percentage of the participants has scores above a score of 25.00?

50% score above the 25.00 if 25.00 is the median.

Is the “range” or the “interquartile range” a more reliable statistic?

Interquartile range is more reliable because it is the range between 2 quarters, and therefore less skewed by extreme data.

The interquartile range is the range of the middle 50%, the range between the 1^st and 3^rd quartile.

Which statistics discussed in this topic measures variability?

Median, range and interquartile range are all measurements of variability?

Sum of X and Y: ∑(15+11)=∑15+∑11

Sum X² :∑ 55≠∑(15)²

1. When the relationship between 2 variables is perfect and inverse what is the value of r?

The value is -1.0

1. Is it possible for a negative relationship to be strong?

Yes it is, at -1.0.

1. Is an r of -.90 stronger than an r of .50?

Yes, because r >.70 is stronger than .50.

1. Is an r of .75 stronger than an r of -.35?

Yes, because .75 is stronger than .35.

1. Is a relationship “direct” or “inverse” when those with high scores on one variable have high scores on the other and those with low score on one variable have low scores on the other?

The relationship is direct or positive.

1. What does an r of 1.0 indicate?

strong relationship r>.75

moderate relationship .40<r<.75

weak relationship 0<r<.40

no relationship r=0