Sampling and Statistics

Question 1

What is population?

Answer 1

complete collection of elements to be studied, the group to which the results of research are intended to be generalized

Question 2

What is a Sample?

Answer 2

a subset of elements drawn from a population to draw conclusions or make estimates about the larger population

Question 3

What is sampling error?

Answer 3

chance difference between what is collected from the sample and how it relates to the true value of the parameter for the population

Question 4

What is the difference between sampling with and without replacement?

Answer 4

With Replacement- each unit that is selected for the sample is put back into the population before the next unit is drawn from the sample to insure equal chances throughout the population to be selected

Without Replacement- once a unit is selected from the population it is not returned to the population before the next unit is drawn (much more common)

Question 5

What is probability sampling?

Answer 5

sampling that uses some form of random selection and every unit of the population must have the same probability of being selected

Question 6

What is simple random sampling?

Answer 6

all subjects have equal chance of being selected

Question 7

What is systematic sampling?

Answer 7

subjects are selected by taking every nth subject from the population

Question 8

What is stratified random sampling?

Answer 8

also called proportional random sampling

population is divided into homogenous subgroups and then a simple random sample is drawn from each, this insures that your sample includes subjects from key groups of the population

Question 9

What is cluster sampling?

Answer 9

population is divided into clusters or areas and a random sample of the clusters is selected

Question 10

What is convenience sampling?

Answer 10

a non-probability sample that is selected from subjects who are convenient or readily available to the researcher

Question 11

What is purposive sampling?

Answer 11

a non-probability sample where subjects are deliberately selected based on predefined criteria chosen by the investigators

Question 12

What is quota sampling?

Answer 12

population is divided into subgroups like it is for stratified random sampling but subjects from each group are not chosen at random but by convenience

Question 13

What is snowball sampling?

Answer 13

subjects are identified by asking existing subjects for names of other possible participants

Used when the characteristic to be studied is rare and finding subjects would be difficult and expensive

Question 14

What is Kurtosis?

Answer 14

the “peakedness” of a distribution, a high kurtosis distribution has a sharp peak and longer fatter tails while a low kurtosis distribution has a more rounded peak and shorter thinner tails

Question 15

How much of all values fall within one standard deviation above and below the mean?

How many in 2 standard deviations?

3 SDs?

Answer 15

68%

95%

99%

Question 16

What is the difference between a positive and a negative skewed distribution?

Answer 16

Positive: mean and median are to the right of the mode and the right tail is elongated

Negative: mean and median are to the left of the mode and left tail is elongated

Question 17

What is an ANOVA parametric statistic?

Answer 17

Analysis of Variance is an internal statistical procedure used to test the equality of means between two or more populations by analyzing sample variances

Question 18

What is the difference between a one way and a two way ANOVA?

Answer 18

One Way- similar to an independent T test but is designed to accommodate two or more population means, only one variable is examined in the analysis

Two Way- used to compare two or more population means with two or more independent variables and it also examines the relationship between the two independent variables

Question 19

What is a Repeated Measures ANOVA?

Answer 19

analysis of variance where all individuals are measured under a number of different experimental conditions

good for when variables that have minimal practice or carryover effects

Question 20

What is a regression analysis?

Answer 20

used to examine the relationship between a dependent variable and one or more independent predictor variables

predicts how a change in one or more of the independent variables affects the dependent variable

Question 21

What is a dependent or paired T test?

Answer 21

a parametric statistical procedure used to compare the means of two groups that are correlated, paired T test is used when samples are matched pairs

Question 22

What is an independent T test?

Answer 22

used to compare the means of two independent groups

example is that an independent T test is used for testing differences between males and females because a person cannot be in both groups

Question 23

What is the difference between a one tailed and a two tailed test?

Answer 23

One Tailed- a test for when deviations from the null hypothesis are only measured in one direction which implies there is only one effect from the intervention (beneficial or harmful) if A value is .05 then all of it is applied to one side of the mean or the other

Two Tailed- deviations from the null hypothesis are measured in either direction from the mean. If A value is .05 then .025 is measured on both sides of the mean

Question 24

What is a Z test?

Answer 24

procedure for estimating the mean of a population or comparing two means when the population is normally distributed and the population variance is known

Question 25

What are nonparametric statistics?

Answer 25

Stats that do not assume that samples come from populations that are normally distributed and do not assume homogeneity of variance

common for nominal or ordinal level data or interval or ratio data that are not normal

Question 26

What is a Chi-square Test?

Answer 26

a nonparametric procedure for nominal data that evaluates the difference between observed and expected frequencies to examine the association or independence between categorical variables

Question 27

What is a Kruskall-Wallis Test?

Answer 27

procedure used to determine if three or more independent samples come from the same population

nonparametric version of the one-way ANOVA

Question 28

What is a Mann-Whitney Test?

Answer 28

procedure used to compare two independent samples with ordinal level data

nonparametric alternative of the independent T test

Question 29

What is sensitivity?

What is specificity?

Answer 29

Sensitivity- the percentage of people who test positive for a specific disease among a group of people who have the disease

Specificity- percentage of people who test negative for a specific disease among a group of people who do not have the disease

Question 30

What is a false negative Test?

What is a false positive Test?

Answer 30

False Negative- test that indicates a person does not have a specific disease or condition when the person actually does have the disease or condition

False Positive- test that indicates a person does have a specific disease or condition when the person actually does not have the disease or condition

Question 31

What is a Negative Predictive Value?

What is a Positive Predictive Value?

Answer 31

Negative- ability of a diagnostic test to correctly determine the proportion of patients without the disease from all the patients with a negative test result

Positive- ability of a diagnostic test to correctly determine the proportion of patients with the disease from all the patients with a positive test result

Question 32

Does specificity help rule in or rule out a diagnosis?

Answer 32

Rule In (SpPIn)

Question 33

Does sensitivity help rule in or rule out a diagnosis?

Answer 33

Rule Out (SnNout)